On the 20th of September, I called the provider to find out if it is possible for me to connect at the rate if the previous tenant terminates the contract with this operator. The operator replied that the connection is at the new rate. This is POSSIBLE if the contract was not signed at this address at the time of activation. No other conditions were agreed. Therefore, the previous tenant must terminate the contract, move out of the apartment, and my wife and I must move into the apartment and connect at the new rate. The previous tenant of the apartment did not mind leaving us the modem (the Deposit for the modem was not paid) and the contract number under which you can pay for the services of the provider. You wouldn't need to waste time if you didn't benefit from the new tariff.
We took the previous tenant to the office on September 30 to terminate the contract. The queue was rather long, and the whole procedure with the road took about three hours. It would have been possible to activate it on the same day, but we haven't checked in yet and to be sure, we decided to enter into a contract after checking in.