Glowworm Boiler Guarantee

[Barquentine]

Does anyone know the law governing terms and conditions given with guarantees? We had to let our thirty-year old boiler be replaced with a modern Gloworm combi-boiler as part of the new extension we had built. The old boiler functioned perfectly for more than 30 years with no servicing - ever!
The modern, up-to-date and supposedly improved quality boiler Gloworm supplied is still working fine after 12 months (touch wood) - but in order to keep the 2-year guarantee valid we are required to have an annual service and pay a monthly fee. Is this one of the many cons used by companies to squeeze extra money out of customers - and are there regulations covering this area in addition to the Consumer Credit Act/Sale of Goods Act?
Many thanks.

[Akakpo]

You can always use an independant Corgi registered engineer and not one from the manufactures who are more expensive. Unfortunately, boilers these days needs to be serviced before a warranty claim will be approved.