I bought an approved used car from a Mercedes main dealer that came with a 12 month manufacturer’s warranty. After 11 months a fault developed which Mercedes warranty service are declining as the fault is excluded in their t&c. I’m disputing that. Should I proceed to making a small claim who is my contract with – the supplying dealer, the warranty company or both? Many thanks.

Have you checked the terms & conditions of the warranty? They all have exclusions. In any case the warranty documentation will show who is providing the warranty.

Any claim is against the supplying dealer (unless not excluded in the warranty T&C's)