Telkom still debit my account after contract ended and terminated

I had a the worse experience with telkom . I had a contract with them for the past two years, now that our agreement has come to an end they continue debiting my account and I have phoned them several times to address this and their agents keep on saying they will sort it out. My credit record is affected by this because it shows that I am not paying and I spend so much money for petrol and bank charges to reverse this debit order. Telkom is a **** and they need to be stopped, they don’t know what they are doing.