Change of quote mid work

MysteryMe

Some red flags here. Sporadic attendance on site, lack of communication, springing a demand for more money once he's basically got you over a barrel.

Is there any indication where the pallet of tiles came from?  Take one of your tiles and go to them and some other local builder merchants and find out if there are supply issues or been significant price hikes. Do any of your quotes give an indication of the area to be roofed? If so ask the merchant how much would the necessary number of tiles cost to give you a rough indication. £8,000 seems a heft chunk of money. Do your own research, don't rely on the word of someone who has already shown themselves to be unreliable. 

domdeath

Thanks for the advice all, this has been really useful and reassuring to get the different perspectives and suggestions.

I had some advice from elsewhere to check citizens advice and it covers the exact scenario I am in:
https://www.citizensadvice.org.uk/consumer/getting-home-improvements-done/problem-with-home-improvements/
He has admitted he made a mistake, this wasn't obvious to me and so I have the legal right to get the work done for the price in the quote.

I have asked for itemised costings and copies of receipts and in the first instance will get him to keep working until he thinks the cost limit of the original quote is up. Then I will tell him I expect him to finish the job and quote the law. Hopefully this gets him to keep working thinking he will get the full amount (and thus hopefully will continue to do a reasonable job).

I will get photos of every stage and confirm it os done to standard with an independent roofer.

If I continue to have issues I will get the consumer ombudsman involved.

Section62

domdeath said:

I have asked for itemised costings and copies of receipts and in the first instance will get him to keep working until he thinks the cost limit of the original quote is up. Then I will tell him I expect him to finish the job and quote the law. Hopefully this gets him to keep working thinking he will get the full amount (and thus hopefully will continue to do a reasonable job).

Beware of making the error of underestimating the ability of traders to work out when they are being conned.  Some traders are really stupid. Most are experienced enough to know all the tricks in the book.  In general when someone starts quoting the law to them the response tends to be less than positive.

The way you handle him should be adapted depending on other factors - including whether he is a sole trader or limited company.

domdeath said:

I will get photos of every stage and confirm it os done to standard with an independent roofer.

It might be difficult to find an independent roofer who will get involved in a dispute with another trader.  They also aren't really qualified to give a professional opinion on someone else's work.  If you want to go down that route then consider a QS or general surveyor - someone whose report could be used in court if necessary.

domdeath said:

If I continue to have issues I will get the consumer ombudsman involved.

Not sure about this consumer ombudsman.  In most cases where there is some kind of building work dispute the situation rapidly deteriorates to the point where one party seeks to claim money off the other - either through the Moneyclaim route, or sometimes through more expensive court routes.  If your roof is still only half-finished you may find the legal process agonisingly slow.

Without having a better idea of the situation it is difficult to comment, but as a general rule, allowing a situation to develop into legal action is not helpful to either side.  Trying to find some kind of compromise is usually better overall.

MysteryMe

At this stage, I would still do your research OP as I suggested. You don't know whether he has "made a mistake" or using that as an excuse to extract more money from you. It's not just the money, it's the not being on site when expected and poor communication so you should exercise caution with him.

If it has been a genuine mistake on his part for the sake of goodwill I would come to an arrangement and maybe agree to 50% of the extra he wants. It's his mistake after all so he should take a hit as well. But I would not pay anymore money until the job was completed. If he starts objecting then let him know you've taken advice and don't actually have to pay him anything extra. 

My gut feeling is this is not a genuine mistake and he's a chancer. He would have known at the time of ordering the tiles what the cost was, if it was significantly more than what he costed for, he should have got back to you straight away, told you he made a mistake on the quote and basically told you that he couldn't do the job for less than X and then given you the option of proceeding or not. He should not be removing tiles off your roof before the new tiles are delivered to your property

What he's done is take a substantial amount of money from you, taken the tiles off your roof and then told you of this "mistake" A reputable roofer does not operate like that. 

Roofing is the most complained about area of building work unfortunately.

MysteryMe

You could speak to someone like https://www.corc.co.uk/   Even if your roofer is not a member, they can offer advice.

If the worst comes to the worst and you find you are £8k down and no roof, they will know reputable roofers in your area who can finish the job (obviously will end up costing you more money) and may well have accredited members who for a fee can inspect work done and produce a report if you wish to go down the small claims route.  

DRP

As MysteryMe says above: "What he's done is take a substantial amount of money from you, taken the tiles off your roof and then told you of this "mistake" A reputable roofer does not operate like that. "

If you've no other options you might have to swallow the extra cost, but not a penny til he's done (or some other way to guarantee he won't find additional costs to add).