Fees for PCR test

Back in September, my roommate tested positive for Covid, so I had to do a PCR test. The contact tracer sent me a code, and I assumed that the costs would be covered by the State. But just a couple weeks ago, I received the invoice for the test. I have now contacted the provider, but I have received no answer yet. Does anybody know whether these tests always have to be paid? If I had known that, I wouldn't have taken the test. I remember back in May of last year, I also had to pay for two PCR tests after returning from a trip to Germany. Back then, they told me that you have to pay for it if you are not in a Mutuelle.