Overcharged gas works

MrManorcat

Hi, I hope someone can help me.
I recently asked a plumber who I've used before to re route the gas pipe from the meter to the boiler. The existing pipe was inside and very accessible to remove and was about 3.5 metres long. The replacement pipe was run from the meter outside across the wall and back in to the boiler. A run of about 3.5 metres. So basically a very simple job with no access issues and not time consuming!.The only thing was I didn't get a quote because we had used him before and I am in the property maintenance sector so assessed the job as being quick and if a water pipe not gas 2 hours max Inc a cuppa would have been enough. So a bill of £345.00 was sent to me for the work? 😲. They work on price per job not hourly rate, have I been ripped off and what are my options in challenging the bill. Look forward to hearing any ideas. 
Regards Mr Manorcat 

Rodders53

MrManorcat said:

The only thing was I didn't get a quote because we had used him before and I am in the property maintenance sector 
what are my options in challenging the bill. 

There's your big mistake.  
Surely if you are in the "maintenance sector" getting competitive quotes is second nature to you?

Questioning the price is reasonable.  If it's not broken down, ask for that breakdown (materials, labour, vat). 
https://www.pimlicoplumbers.com/rates  £120 per hour plus parts plus VAT - so your 2 hours estimate = 240 +48 = £288 labour alone...  Labour rates vary wildly by location, of course.
Does a pipe replacement (upgrade?) require Gas Safe Certification and Building Control?  Extra work (time) if so?

To never use this Gas Safe fitter again, nor recommend him/her to others you know, would seem reasonable come-uppance for the perceived over-charging, if unhappy with their explanation of the Invoice price?