Cancelation of ADSL

Telekom service is pathetic. Cancelled my adsl service last year with them. Still getting billed. Tried canceling it online. Their website not working keeps on giving error. Phone get a reference for the call to cancel. Go in to check if they cancelled their Is nothing on the system. They cancel it while I'm there. I get my bill and I am still being charge adsl and I have a wifi router. Got a reference for cancelation via telecom and instore for adsl. Wow, it seems they can't do their jobs properly.