What I would do, is go to a main dealer, explain the symptoms, and see what they suggest. If they confirm that the Kwik Fit parts are sub-standard, I would have them replaced and save the parts. I would write a polite letter to Kwik Fit head office, explain the story, and ask if you can return the parts. (This is what I did for the Saab exhaust, and Kwik Fit were very reasonable about it.)

Thanks, I loved my little Fiat, but sadly I don't think they adequately rust-proofed them against UK road salt. The door sills rusted through by eight years old, and although I had it repaired, it still continued to rust, and sadly went to the breakers yard at ten.

Good luck with Kwik Fit,

James