Baxi solo wm rs Boiler banging and noisy?

Hi, a few weeks ago i noticed the boiler firing up in the middle of the night and the radiators becoming hot when they were not asked too. All controls were off. I called a repair man who changed the controller clock for £60 but nothing changed still the same. So i am left feeling the old one didnt need to be replaced.
I put it down to the frost setting in the extreme cold.
The boiler is in the loft and yesterday when the boiler fires up it starts bang and it sounds like rats running around up there. Could it be temperature thermastat? could problems be related? Would appreciate any help offered before calling someone out again.