Chaffotaux Mauray britony boiler?

The boiler started making a click, click, clicking noise before it broke down. 14/12/09. It still fires up but does not provide heating or hot water because it cuts out within seconds. An engineer for HomeServe called out on 17/12/09 couldn't repair it and ordered a PCB, not sure whether this is a printed circuit board or process controlling board. He returned 6 days later with the part and still could not get the boiler to work. This time he ordered an egnita ionization electrode but the parts dept are closed until the 4th of January. No one can tell me when the engineer will return with the part and I am concerned he will still not be able to repair it. I am desperate so I am going out tomorrow to purchase a Worcester boiler and get it installed. Are Chaffotaux Mauray boilers difficult to repair and can anyone tell me why it takes so long to get the parts? The boiler is 8 years old