Fiat 3rd Year "Dealer Warranty" Question?

I have a 30 month old Fiat thats now in the "Dealer Warranty" period. I bought it new and it comes with a 2 year manufacturer warranty and this "3rd Year dealer Warranty". I now possibly need to make a claim for a mechanical part but will the dealer honour the warranty if I didn;t actually get the last service done by Fiat? It was serviced at a VAT registered garage though, using Fiat parts and I have the stamp in my service book.