Why is maintenance work refused

Acceptance of maintenance and repair costs for our gas boiler refused.

Hello dear forum members,

I have just registered because I currently have a problem.

We are a family of 5 and we relate to ALG2. Both my wife and me. Our children are students. There is currently no further income.
I (m) had a fixed-term employment contract, which unfortunately was not extended. At the moment I am actively looking for a job. We have been receiving ALG 2 for a long time with short interruptions. Wg job. or were we z. Part of the top-up. So much for the general conditions.
We live in a house (property).
As is the case as a house owner, you should let your thermal baths be serviced from time to time.
We didn't even know that the maintenance and possibly necessary repairs of a thermal bath could be taken over by the job center.
Therefore we did not submit an application. I had the fitter come to do a maintenance. Should only take an hour. Since the thermal bath had not been serviced for a long time and I knew the safety valve was probably broken, this made sense to me.
During the maintenance, the fitter discovered that the expansion vessel is defective and needs to be replaced. I suspected something bad and asked him about the costs. He said the vessel costs around 50 € which in retrospect turned out to be correct. However, he also exchanged other parts. As already mentioned, I knew that a safety valve was probably defective, as filling the system had only been possible up to a bar for some time.
After the fitter had been there for 3 hours and all the work had been done, the bill came with the shock of € 498.
I had to swallow first. I was expecting something bigger. But so much. Above all, I had instructed the fitter to only do what was absolutely necessary. I was there all along. He could well have told me that the bill could be bigger. Since I had found out through Internet research that maintenance costs are covered, I asked the plumber to split the bill into maintenance and repairs.
Out of sheer desperation, I went with both bills (188 for maintenance and 310 for repairs) to the solidarity-based aid to get advice.
I was told to submit the invoice to the job center with the request to take it over. Now after 2 weeks the shock.
The takeover was completely rejected.

The decision is based on Section 24 (3), second book of the SGB
You have submitted the invoice from company XXX.
Basically, the application must be made before the benefit. In your case, this means that you should have submitted the application for assumption of the costs before this work was carried out. Furthermore, you would have had to submit 2 cost estimates so that the job center could have seen which company would be cheaper. In addition, an appraiser commissioned by the job center should have determined whether the repair would have been necessary.

I complained to the company about the high bill. (Without saying that I can't pay them) The fitter told me that all the work was necessary. The expansion tank was defective. The electrode block had to be changed. Etc.

Now you can say I was stupid. I'm angry with myself that it went that way. On the other hand, out of ignorance, many things were simply not known to me at all.

I will definitely contradict it. Does anyone have experience with something like this?
I have to say that I adhere to all duties.
Since we have been using Alg2 (previously as a top-up), we have never applied for anything. Except for now education and participation and recently more needs because my wife is pregnant. We are probably the cheapest ALG recipient for the job center, as we have very low NK. But now that you need help ...

Maybe someone has an idea