I have a Valliant EcoTec 831 installed and maintained by a well known company with British in their name. It is well out of warranty and I have an agreement that provides an annual service and breakdown cover with a £50 excess. It has never missed a heartbeat until a few days ago when heating and hot water went, an F75 code appeared and water was dripping from the casing. It was last serviced 20 months ago and they would not come to service during the last year because of the pandemic and I understand that. They came pretty quick because we are elderly. The engineer replaced 3 parts. The worksheet states 1)Leaking diverter cartridge 2)Low water pressure switch faulty 3)Expansion vessel was shot. He told me he had left the parts and when I said I only have a £50 excess to pay, he said I would receive an invoice for £150 as 3 parts were replaced. I said it was only one breakdown but he said it was 3 parts that were not linked and they would be treated separately. He said one part could have been going and not causing any problem. Can I ask a question please? Are these parts linked causing a domino effect? And if the boiler had its inspection service 8 months ago, would it have picked up a failing part that would have stopped the domino effect? Thoughts greatly received as £150 seems a bit high handed when I didnt even get my annual service.