"Sondertilgung" is not an "early repayment," since the "Sondertilgung" (if available) is contractually regulated. "Early repayment" refers to repayment before maturity that is not contractually regulated. However, there are also contracts in which "early repayment" is completely excluded, i.e., repayment cannot be made even with the acceptance of a prepayment penalty.
Otherwise, the regulations sound rather strange, which is why the question is justified as to what kind of loan agreement this is. Loan to a consumer or a company?