Upset with the whole process

My first and only time using the bca at Belle vue in Manchester to buy a car, In the end I bought two cars from the proceeds from my insurer after my other car was crashed into, I bought a Polo for my partner and a Renault Megane for myself which is what I really fancied this time. Low and behold a Megane comers through toward the end of the days auctions and I will was impressed as naively it looked good and clean, the 'bca assured' report that I now know isn't worth the paper it isn't written on claimed there were no faults on the car, because of this I bought the car, after paying and then receiving the car and taxing, insuring straight away to make it legal to drive away; every problem you could think of started appearing within 2 days, including it not recognising its smart card key, I contacted the belle vur branch and was passed around until head office got in touch and said I could have a full refund, not before paying £50 to valet it when I initially got it home, I took the car back and waited 10 days to find I only received a partial refund, after speaking to them I nwas told this was the returning bca assured fee of £51 so I could return the car if it is fault, what I can't understand is that the assured report was wrong so therefore i was mis-sold this car, to top it off it wasted a month of tax which took months to return from dvla as I had to give reg cert back to them it never got registered in my name, the £50 valet, fuel and wasted time, they ignore my letters! Never use again