As said I did not want the cover in first place, it was closing the stable door after the horse had bolted. The micro switch failed in the motorised valve, this resulted in the pump running against a closed valve so pump also went, the pressure had dropped in the solar panels, this required topping up, likely due to power being turned off so pumps not running so over heated, and also a new radiator as nothing in living room and new gas fire in living room. So this years there was a lot of time and effort spent to get the heating up and running. So it was unlikely that anything further would go wrong this year, and to fit the new radiator the whole system had been drained and refilled with new inhibitor put in.
So I knew there was a fault with the thermostat it showed wrong temperature, but still worked, but other than that old but A1, so I did not see point of getting a maintenance contract. However my brother-in-law insisted he was fed up with travelling 180 miles round trip to fix central heating in a hurry, so he insisted at £125 it was good value so bought it. However they said the system needed flushing, seems unlikely with fact all water was drained and refilled when new radiator fitted, and they wanted £250 to do this, so he got another plumber to do it, far cheaper, they returned, took a water sample sent a copy of findings and said it needed flushing again.
I read this as if you don't use us, then we will not take over the maintenance, although they say we can get anyone to do it, but to date it has cost around 500 miles travelling to give them access don't know how much that costs, but would guess around £70 just to open the doors, and for the estate agents central heating tested and reported as A1.
So I have told brother-in-law he set it all up against my advise, it's up to him to sort, seems he's told buyers there is a maintenance program in place, so now he wants it to run, however really makes no sense.