Anyone has a service manual for a Siemens HC744233U?

​Our Siemens HC744233U electric stove has never worked properly! The IR cooking burners has never been putting out the expected heat. Even at full power they are never heating continuously - and even simple cooking lacks heat. (Not quite sure if they are “fixing” some thermal design errors or it has indeed always been defective)

The oven seems very simple (“dumb”) with a perceived mechanical function switch and seemingly a mechanical thermostat. But lately, the grill element is erratically turned on (=burning the food) even when using the standard oven functions. >:-(

Siemens/Bocsh/Neff/Gaggenau support is unwilling to release any information. (Great attitude if they will make sure to loose me and my peers as customers!) But they will send an expensive technician (that definitely will not be worth his or her pay - and probably will just state “buy a new” - and if they are fair recommend another brand! ;-).

Anyways, I’d love to see a schematics or a service manual! This will definitely make the repair effort much easier… Has anyone gotten their hands on one? Or has experience with similar behaviour of other Siemens/Bosch stoves?

Thanks in advance!