Contact Phill at no road club he has an excellent selection of wheels and tyres to suit with very competitive prices I have just fitted a set of 20 inch wheels with a set of duratecs grip is very good in mud

I had the same issue take the negative lead from the stupid nutsert below the battery and put it on a better bolt. Mine now works

My2012 did the same I found that I had it set to 28 a lot of the time and the only way to get it hot was turn the blower to max
My 2015 is much better I have not turned it up past 22 yet but we shall see when the weather drops off again