How old was your Corolla? Did they admit to mechanical failure or did you get inspected yourself elsewhere?
My Corolla was on a 55 plate and it was last year it blew at 28k. I had to really fight my corner and it was hard but initially on inspection they tried saying it was caused by a lack of lubrication. But after showing an ex rally driver who's held in high regard by Toyota he said it was a load of crap and it was blatantly mechanical so a few phone calls from him really got it sorted.
It's all about what you can prove and hopefully you have all your servicing and receipts etc because they will try and put the blame on you.