Servicing/wiring check in north west London

  1. My model of MX-5 is: NA Eunos Mk1
  2. I’m based near: Watford
  3. I’m looking for technical help or recommendations on: I would like to know if there is a recommended garage in London/Home Counties for standard servicing but I am also looking for recommendations on a wiring specialist- even when fully charged if battery is left connected for 48 hours then it is flat so I am assuming I have a wiring problem as the battery is less than 12 months old (purchased from mx5 parts)