I bought my first financed vehicle through them, think in 2003/4 - it was also where I learnt never to trust a salesman word.
My girlfriend at the time was driving behind me when I took the vehicle to be checked a few months after when moving insurance, she said my back wheel was wobbly, had it checked out, something like the back axle was cracked, and I found out it was in a serious rear-ender. (I had been in a minor accident where I knocked the front driver side wheel on the road side, I even took it to two different places to confirm it was in no way related).
I also noticed the tape player wasn't working within the first month, the salesman basically told me to sod off I should have checked it before buying the car. Needless to say, bought the car in March sold in September.
Ever since that day, I send every car for a AA/Dekra test, and just hope they pick up any major issues.