2006 Renault Kangoo radio stops working when cold and now fuse wont stay in

This has happened every time there is a frost, the radio stops working. I take out old fuse, put a new one in & it works again, usually. Halfords have confirmed that there doesn't seem to be anything wrong with the old fuse. Now however I cannot get a fuse to stay in, even in any of the other spare slots. Neither could the guy at Halfords. Everything else seems to be working except the back window heater. I dare not take out any of the other fuses in case I cant get them back in.