I beleive there are many very good, competent mobile engineers all over the UK who would do the work and accept the warranty fees. Many of whom are fully trained by ALKO Truma etc.and are fully insured. Independent business people who will do a good job. It is not the dealers who prevent these guys from doing the work. It is the manufacturers who do not recognies the service stamp as valid or authorised.
Buy a new car and as long as you have it serviced to manufacturers specification useing approved parts, then the warranty is valid. I understand this was a ruleing in law!
I purchased a new caravan and as a good boy I took it to supplying dealer for 3 years for service. I paid for lots of things to be put right that I never knew were wrong and at year 4 I used an independent to service who found damp that was proven to be there from new. I paid to get it put right. the dealer ( a household name) missed it for 3 years. My mistake was trusting the workmanship of the dealer. Never again though. If I ever buy another new van then I will not ever trust the workmanship of a dealer and I would buy the van assuming I have no manufacturer warranty as I will use the very good but non authorised independent who will at least find the faults early days. As an independent he is able to undertake all the component waranties for Truma and alko etc. Surely I should be able to take it to a competent serviceing engineer and not void the warranty rather than take it to an incompentent dealer just to maintain the warranty
I suspect it is more the case that you hardly have a manufacturers warranty and all you get is the contract in law stuff with the dealer because he is the man who took your money. I beleive that any authorised dealer or repairer can do warranty work but only the suppling dealer is oblidge to. surely this is simply sale of goods act, not a manufacturers warranty in any way that is understood by the consumer with regards to any other product they may buy.
Just my opinion and take