I'd say they would answer that question no problem if you ask them directly.
If you're tied into some sort of contract with them, I think i'I run a mile.
I'd rather have an independent boiler installation company and keep the freedom of choosing my gas supplier.
Is your existing boiler completely knackered? Usually best to ensure your home is fully insulated and draught proof before installing a new boiler.
RegarlRega of your decision, always get your boiler serviced annually by a company registered with RGII.