Billing problem

I am almost tearing my hair out. Ref order***A was for the R699.00 promotion 20mps uncapped and was installed on 23 April. I received a bill where I was charged more and I called billing who advised me that what they had on their end was a normal package and that I should call sales to rectify and capture the correct package. Nightmare began on th 12 May /22 May/23 May/25 May where I have called sales and they refer me to billing and billing refers me to sales with noone resolving the issue. I was told by Sibusisiwe Ngcobo on the 12th, Portia Msomi on the 22 May, Calvin Sapolwami on the 23 May that a manager would call to resolve the issue and noone has called. I spoke to Lemile Tiyo on the 25th who advised that it was in order and should call billing to send correct bill and lo and behold , billing said the problem is with sales. 26 May I called sopke to a Nosipho who is completely clueless. I am at my wits end and will not pay this bill as it was wrongly charged