Most hvac company’s will do electrical as well. But for the money I would fix it myself. They don’t stock these things on there trucks (service Trucks anyway) i asked where you live because I was going to offer to help but with the holidays and family in town the weekend would be best for me. If you could get the disconnect changed and wire fixed. We could talk over the phone to see what’s wrong with the unit I could order parts and come over this weekend to get you going but I didn’t know what your time frame was. With small kinds it’s best to get the heat going as soon as possible. (No charge other then parts, this reef family has already been great to me it’s the least I could do to help out a member.
You could also open the unit up and look for more bad wire could tell you where this started. Might just be a bad disconnect. And breaker!