Electrical issue is one of the thing that most of the workshop not keen to attend because diagnosing it requires a lot of time, and sometimes the fault could be as simple as loosen connector. Not financially rewarding actually.

If you can get one workshop doing that for you, cherish it. If cannot, SC is always the best place to go. Downside is they might need you to leave your car there for weeks to check. And they might according to protocol had to remove non original wiring for troubleshooting. Pros is of there's nothing to replace, they don't charge you anything, probably except OBD diagnosing fee, which is peanut compared to the work technician put into your car.

Sometimes I wonder should I service my car in sc just to make my conscience feel better. They used to fix my knock sensor engine light issue for me without any charges. Because the problem disappear after they disconnect and connect back every wiring point from ECU to knocking sensor.