The supplier has incorrect meter numbers in the system - what to do?

Bayernwerk and EON took almost 2 years here to properly record my cascade in their system. Before that, I always had to pay household electricity including heat pump consumption on top (of course, the heat pump consumption alone was also calculated)

I can't believe it - that's exactly my combination and my experience! Then definitely check if they have even classified you under heating electricity, because when they finally accepted what a heat pump cascade is, they recorded everything as household electricity. That cost me another six months and many phone calls until they finally admitted it and had to pay me back a four-digit amount.

One could almost suspect intent, but my phone calls gave the impression that they really don't know any better. That doesn’t make it better, just less criminal.

Thank you, so far yes, but I will keep an eye on it. Thanks for the hint.

That it took so long to get to the one competent and authorized person was just incredibly annoying. First, you have to fight your way through the waiting loops like in a computer game and the call center long since outsourced from the parent company. Until you finally reach the headquarters - the supposed final boss - but: the friendly lady said: I will check this and get back to you. To my great surprise, she actually did so the very next day and had already initiated the refund. It can go that fast then. Unfortunately, only after almost 2 years.

That letters were simply not responded to at all, I find very disturbing.

A small update from this front: I spoke with the electrician today. The numbers are apparently really wrong. Since we built with photovoltaics, meters were apparently installed and then immediately replaced again. It’s apparently always like that when you get photovoltaics. Although I don't understand the purpose of this, and it must have happened within a very short time - but now we know more. I have now tried to switch to another provider with the old meter numbers. Let's see what happens.

But how are the meters connected? Can your heat pump use photovoltaic electricity or not?

Since we installed photovoltaic, meters were apparently installed and then immediately replaced again. That’s apparently always the case when you get photovoltaic.

That a meter has to be replaced when installing photovoltaic, I only know if it is one without an anti-reverse feature. Such meters should actually no longer be installed for a long time. But well, if the grid operator puts in their program "Always replace the meter with photovoltaic installation," then it gets handled that way, whether it makes sense or not.

Was the same meter model really reinstalled or afterwards some supposedly "smarter" meter? It could be that the grid operator reserves that for photovoltaic systems.

I have now tried to switch to another provider with the old meter numbers. Let’s see what happens.

Are the old meter numbers still listed with the grid operator? Because the electricity provider will go to the grid operator and say: "Will you give me the readings for these meters in the future?" and then the grid operator has to nod.

But how are the meters connected now?
Can your heat pump use photovoltaic electricity or not?

Yes. That is "Power To Heat", the term is probably established by now but somewhat misleading. We have a total electricity meter and a separate meter for household electricity. The heat electricity is determined by subtracting the household electricity from the total electricity.
The photovoltaic electricity first goes into the household (and battery), then into the heat pump.

Are the old meter numbers still listed with the grid operator? Because the electricity provider will go to the grid operator and say: "Will you give me the readings for these meters in the future?" and then the grid operator has to nod.

Yes, that’s why I also used these values. No one knows when they will change that in their system. I would like to retroactively switch to the new provider, as they are somewhat cheaper and above all the installments make sense.
With the basic supplier, I can only lower my installments online by about 20 euros or so. How they come up with these crazy installment amounts (400€) is a mystery to me.
My sister had the same problem with them and has been struggling for over 2 years to get her refund (four figures). That’s why I certainly won’t pay such high installments to them. Let them get their interest-free loan from someone else.