contract phone

I had a very bad experience with telkom i was having a contract with them of which was finished last year january but there continue deducting the money so I had to go to their branch (park station )to ask what was happening there ask my ID there said there cancels there won't deduct the money ,the following money there continue then i went to( grand quare) with my ID they did the same but following telkom keep on calling me saying I'm owing them 600 which I don't know how cause my contract and them is finished .so now when they deduct the money I reversed it back .im very disappointed if I would have been known that this company is like this 😔 I was not gonna commit myself with them