Potterton Performa 24 combi boiler on off cycling problem?

My boiler has broken down with the same problem of no hot water or heating after just a year and five months from when the engineer said the (circuit pannel) was faulty and he repaced it. Now he has to do the same job and there is no garrantee this is not going to happend again. The cost is a lot for me. Is this a normal problem? Please help.

Ete
May 2009

check fan venturi for blockages and tubes to air pressure switch and pressure switch operation

STE
April 2009