I have claimed twice from BCA on BCA assured, first time - car would not select 1st gear stationary, they refused to take the car back or repair, after their engineer came and inspected. So I took the car back to the BCA branch where I bought it from with paperwork and both keys. Asked the manager to have a look, he said he won't and the AA man has a day off, I demanded that someone has a look as I'm not taking the car back from there and want a full refund. The manager inspected and made some lengthy phone calls. He then agreed to take it back.
The other a Golf DSG, report all green. Got it back and it was shaking like a leaf on idle, they wanted me to get it diagnosed and report back. I refused as I didn't want to spend any money on it. They got it picked up and checked the garage couldn't make out what was wrong with it after about 2 months. Got a full refund with that one as well.
Don't give in or they will have not honour anything.
(I buy about 100 cars a year from BCA)