Contract not ending

I had a contract with Telkom for internet connection account ***,for R196 a month but during the 24 months of my contract my account will be debitted double I tried to contact them with no luck now the 24 months period has passed and they kept debiting R40 from my account until I stopped it from my bank account. But now even worse they starting againg trying to debit R595 from account,making more charges to my account,I don't know what is it that I still owe them