Boiler failed completley after 18 months contact c...

Boiler failed completley after 18 months contact customer service to arrange a repair this is going to take over a week to repair.
My heating engineer who installed the system would have come out to repair but cannot repair boiler whilst under warranty as this would invalidate it
My question is he installed the boiler why can,t he repair it under warranty.
Have now moved out of house into caravan to keep warm on the drive would not go for Worcester Bosch in the future and would not recommend to anybody