Billing issue

I did not get billed on the 1st of December , i was wondering why that happend maybe its cos i did upgrades at the end of november, so i called in to find out whats going on. Spoke to a lady by the name of Zanele Shezi, she informed me that i was in arrears and took me off topic. So i sent through my bank statement showing that the arrears amount was cleared up months ago and i was still getting billed as per usual all the months thereafter. After sending through my details i got no response, i sent a follow up email and still no response.