Remove a starter button?

[Cobbler]

Have an MX5 Mk1 with a starter button in place of the cigarette lighter. Want the put the socket back for phone/sat nav, would this be a big job for my local garage to sort out? Not sure I feel confident messing around with the electrics of my car.

I'm in North London if somebody knows the best people to carry this job out?

Cheers.