Ferroli Optima?

Recently having switched on my boiler I found there was no hot water or heating, not being a bright spark I called out a ferroli plumber who seconds after opening the boiler up identified that I need a new PCB at a cost of £250 which he then dropped to £210 cash !! Having played with a few buttons and gave me the usuall talk I agreed to have it replaced. Can someone please tell me how not to get ripped off by these guys and have a better understanding of my little boiler.

Many thanks Lee.