AA does not want to honour the claim

I've had the worst experience with AA Warranties. My claim was rejected today even though they are aware that my car had a problem and the garage was able to identify and fix the problem. BMW originally wanted to replace the whole engine but i tried to find another garage because i was not conviced that BMW did a correct diagnostic. The garage has really helped me at a lower cost but AA Warranties keepson rejecting my claims. What's the use of paying for the warranty if i still need to pay from my own pocket if there's a problem with the car. This is the second claim that has been rejected. I trusted the warranty but right now im not sure if i still want to renew my contract when it ends in December.