Vodacom poor service

4 month ago i phone cancelation department to cancel an contract which i have had from 2010 i even phoned from the vodacom shop aswel to cancel it. But now im being phone by debt colecters weekly everytime i exsplain to them that its cancelled and that i have stoped the monthly payment by the bank because its cancelled. Very poor. 11 years no missed payment no my name is tarnished due toe someone not doing their job. Quick to receive the money.