Handed over to layers for no reason

I had contract from cellc, then on 17 august 2015 I made premature cancellation and they told me that I must pay the amount of R3453.11 I did pay the amount and I call the customer care services and notify them about my payment,they told me that it will be cancelled after 24 hours as soon as the money reflect on their system. After that 24 hours I received message from cellc to notify me that they received the money so cancellation will be done.indeed it was done successful. Then i was out from cellc i did'nt owe them.Then on 28october 2015 I received the call from cellc the caller was Ramikosi.this lady was very rude to me she not even want to listen to me she said I must pay the amount of R3350.00 that I owe for cancellation, I said to her I have already paid and I still have slip with me.she did not want to listen to me.she said if I don't pay she will hand over to lawyers. then on 31 October 2015 cellc debited my account with R1731.56. I went to cellc store festival mall no one was willing to assist me I call customer care services they also can not help.they gave me email address to email my slip but the email was invalid. Now I want cellc to pay back my money