Account

I paid my account of R1200 on 4 September 2015 from a FNB Account using my cellphone number as reference which was apperanly wrong, i should have used my account number which I didnt have with me at that time. My line has been blocked numerous times, and the proof of payment with the correct details on it has been sent a million times, but still they cannot allocate my payment to my account! I was due for upgrade in October already, and I get messages everyday that I must go to my nearest store to upgrade, but when I get there I have to hear that my account is in arrears and I cannot upgrade. My account is up to date!!!!! Can you please tell me what more must I do to sort this out, or is my only option to cancel my contract?