Electric hook-up switch - help please

blacklabAlf

We're newbies to caravaning, just bought a rather old, but good condition Compass Rallye.  The only problem is the electric hook-up switch seems faulty, when I connect to the mains, the switch doesn't always work.  Can anyone recommend a reliable person or company local to Huddersfield who could come out and fit a replacement? Much appreciated - Jez