New Kichen - Section 75

Morning
We approached a company to design and refit a new kitchen, we paid the initial deposit of £300 on a Barclay Credit Card on the 16th of June, this was to hold the deal for the kitchen.
We arranged a re-mortgage and received the money on the 1st of September, the kitchen company wanted all the money up front, after speaking with Trading Standards I was told this is now the norm, but it was against my better judgement.
The total cost of the kitchen was £16200, we paid the remainder £7800 by debit card and the rest via MBNA credit card.
The kitchen was started on the 12th of September, during the build, we have been kept in the dark as to who is turning up, when and what is being done. the plaster is bubbling on the walls, units have been damaged, our quartz worktop is damaged.
The tiler arrived Friday 7th Oct to fit the wall tiles, took one look and left, the manager from the company came out and promised things would be dealt with. He said the floor tiles would be laid Saturday (8th Oct) and the plasterer would be out to see what is wrong.
Saturday tiler arrived, again took one look and said this is a joke right, rung the company and left, the plasterer didn't even turn up.

We emailed the company on Sunday saying you have until 21st of October to complete the job otherwise we will be instigating Section 75. They've agreed to have the job done by this date however they are saying that I turned away the first tiler which is incorrect, it's up to me to find out why the plaster is bubbling

1. As I've used two credit cards which ones liable, do I use the one I paid the most on
2. If we did use Section 75 who do we approach for the independent review, how do we do this, how much approx. would it be.
3. If the kitchen people do finish and say 6 months down the line the tiles fall off the wall or it bubbles again, do we still have recompense with the credit card company etc.

Many thanks for your help
Robert