why cant my payment be allocated? Christina Royine - ***

good day, i paid Cell C directly to Nedbank with banking details and ref no provided. still got threating messages that they will disconnect me. i emailed proof of payment and called them. got told that incorrect branch code was used, although its also NEDBANK and the account no is correct. my cant they pick up and allocate my payment??? what has the bank code got to do with the account no??? its the universal bank code of Nedbank that was used. Please Cell C.. can someone please explain to me why cant they allocate my payment?? the payment is in Cell C's account!!!