Information on the subject of collection fees
Basically you have to pay at the time it was agreed. Your contractual partner may also only ask you to pay at that time. However, from this point in time, a debt collection company can be commissioned. This usually only happens after a first reminder has already been sent though.
Attention: a reminder is actually not necessary, if you have not paid at the agreed date, a debt enforcement could theoretically take place.
According to the law, 5% default interest is owed, unless you have agreed a higher interest rate. The same applies to reminder fees: these are only owed if you have accepted them, e.g. in the general terms and conditions, and the amount is specified there. If, without an agreement, more late payment costs are demanded than are covered by the 5% interest rate, the creditor (he demands the money from you) must prove how these costs come about. This is often too difficult. The costs of debt collection companies must not be added to this either.
Other imaginary costs such as "legal advice costs", "customer costs" etc. must not be charged. If, however, you have been rightly pursued and debt collection costs have arisen, these may also be demanded by the debt collection company. It is important not to be intimidated, as this is the tactic of the debt collection companies. Do not let yourself be pressured and let a professional look at the bill before you pay, even if you are threatened with debt collection.
You can do this here if you have legal protection insurance from MyRight, and here if you don't have one. Both within 4 hours. If you would like to clarify such and many other uncertainties quickly with a professional in the future, you can insure yourself here.