Still receiving bills two months after DSL contract cancellation!! (customer number DE16xxx51)

Previously I requested the cancellation of my contract, and I received two emails from you later confirming that you would terminate my contract at 28th February 2019 . However, I keep receiving bills charging for connection fees (for March and April) even after my contract is terminated!

I called you last month to make sure this will not happen again, yet I receive another bill via email today for April's connection fee !

This is totally unacceptable. Could you tell me what's going wrong here? My customer number is DE16902451.

Thanks

Please check again your last 2 bills. One must be with the charge for march and one must be the same charge but with a minus before.
The basic fee was calculated in advance. With the last bill, the basic fee should be refunded again.

Hmmm...looks like so. The bill for Feb. is 29.99, while the bill for March is -29.99. So I guess that means my billing account is balanced now?

Please check again your last 2 bills. One must be with the charge for one and the other.
The basic fee was calculated in advance. With the last bill, the basic fee should be refunded again.
Hmmm ... looks like so. The bill for Feb. is 29.99, while the bill for March is -29.99. So I guess that means my billing account is balanced now?