A misunderstand between myself and my network provider Cellc

On the 26 of January I paid the amount owed on my CellC account of 320 rand I contacted CellC asking if they received my payment ther response was no.I faxed and emailed them my proof of payment they still told me they never received it. I also have them my new banking details so they updated it and cancelled the old account it was because funds was withdrawn from my account since last year November 2017.My phone has been disconnected since yesterday and I don't know what to do or say to convince these people that I have paid my account.Please can you assist me with this matter Kind regards Yolanda Petersen