central locking and elecric windows not working

hi guys ive got the same problem as i had last year ,central locking and electric windows not working at all,thouht it was a fuse last time put after many headaches took it to the stealer who charged me 35 quid and told me that it was a dodgy control unit connection,i could see the mechanic through a glass door and it didnt look like he did anything major,so does anybody know what i need to look at for a dodgy connection?i loathe to have to go back and pay for a second time especially after it being so soon after the last time.any help would be very much appreciated,its amazing how these things that we take for granted can be a real pain in the butt when they dont work