I paid by debit card.

Hello all. This is my first post but have been reading some other posts and been really impressed with everyones willingness to help so I am hoping some of you may be able to offer me some advice. I will try and keep as concise as possible! I bought a car at the end Dec last year, Audi A4, 55 reg with 98k on the clock with FSH. A week in brakes failed and I took it to my local garage who said brakes were only 50% efficiency and would recommend new pads and disks all round. Took it back to dealer bought from and they only agreed to replace front disks. By this stage I had also noticed that the heating system was not working which they said was working fine on all their tests (god knows how as it was on 29 degrees and blowing stone cold air). 2 weeks later car breaks down and recovery say that there's a major water leak. Goes back to garage again who say it's a water hose pipe cracked and they have replaced it. 2 weeks later and the car is still losing coolant and heating still not working. Goes back again at which point they say they don't know what it is and send it to an audi specialist (not main dealer). They find that the radiator is blown and that it needs new radiator, water pump and thermostat which they do. 3 weeks later still losing coolant the Audi specialists take it back again to look again, they find no leaks on external pressure testing and conclude that it must be internal, most likely head unit or gasket. By now I am hacked off and have been without the car some 20 days in 2 months and offer the dealer the chance to buy car back from us for £4500. They refuse and the original dealers then take it back from the independent people as they want to look for themselves. They then say it's a tiny crack in a pipe next to the head unit which they have fixed. In-between this front brake pads have shattered on me costing me £95 to fix. There's bit more to this but that's a brief outline. It's been back 5 times and still not fixed. Roll on 3 weeks and it's still losing coolant. They now refuse to discuss by phone and will only respond to a letter. I have just drafted a letter saying that there is still a problem and despite being given several opportunities they have been unable to fix it and giving them 5 days to offer me a suitable and positive resolution. Am wondering if we have a chance in getting our money back through SCC? I have lost faith in them fixing it so don't really want to give them a 6th opportunity to have it back (unless they sent it to main dealer at their cost maybe). Any advice on how to proceed would be much appreciated, and thanks for getting this far if you have.