Truma Combi e4 failure - help please

Hi I wonder if anyone could help me out

Our three and a bit year old Warwick Duo has a Truma Combi e 4 and last time out the right hand control started flashing red on electric use and it was not heating air or water. The handbook says a failure of a) check 230V operating voltag (easy and checked).. b) check 230V fuse and replace if necessary, c) reset overheating protection - Allow heater to cool, remove connection cover and press reset button. There are diagrams for the fuse replacement and reseting the overheat protection, but it states that the fuse must only be replaced by an expert!!!!! 

Now I am not that practical but I have been under the metal heater cover, which is under the offside bed, to replace the "plug" for the 4th heater outlet a few times :-(( and found that quite difficult as I couldn't work out how to remove the cover completely so I just lifted it enough to get to the plug. Last time it came off I asked the dealer to fix it back permanently (ha) and (touch wood) it hasn't come off since then, but I keep an eye out for it. If it's not too difficult I wouldn't mind trying to reset the overheating protection but I would like to find nearer reputable repairer to fix things and do servicing etc. I live in Rochdale.

Any advice or recommendations would be most welcome.

Thanks in advance