Arcam C30 pre amp repair

Can anyone suggest a credible service agent in London/South East that can look at an Acram C30 pre amp that has lost its output. Arcam are telling me to take it to a dealer and they will charge a flat rate of £300 irrespective of time and cost of parts and there is 2 month turnaround. Want someone that takes pride in their work rather than lashes something up.