Heating maintenance contract - how much should it cost?

Is there a website where you can compare maintenance services for heat pumps and get offers? Or can you contact some kind of "chamber" that represents individual craftsmen? I have had bad experiences when contacting individual companies and don't want to have to act like a supplicant?!

With Dimplex, everything is handled completely by the manufacturer. The contract is concluded with them, and then partner companies on site are deployed for the respective order.

No desire to have to appear as a supplicant?!

Then you have to wait until the current boom is over. As overheated as things are at the moment, it's only a matter of time. At the moment, heating engineers act like lords of the manor.

I only took out such a maintenance contract because of the warranty, ...

Yes, the same with us, and the warranty has already paid off. A defective part was replaced without any problems, I have to check what it was. The heat pump had completely failed in the middle of a cold winter weekend, so worst case, and everything paid off. Meanwhile, the system is connected via the internet with the manufacturer and our plumbing specialist company, so they are immediately informed in case of errors. That cost an extra one-time 100 EUR.