Heating Temp problem Ferroli Maxima 35c?

I have an issue where the heating temp will not reach the dsired value. I set the heating temp using the dial to 68c (this was original value set by installer, found it in his service manual), the temp will then start to rise normally gets to the mid 50's and falls back to the mid 30's. It has never did this previously in the 4 years I have lived in my home. The radiators start to warm up but never get hot. There is no fault lights on the display and the rooms in my house are cold.

Anyone any ideas? I'm currently waiting for a local agent to c all me back as the boiler is out of warranty.