Charging for contracts that have expired, Dissapearing DATA and AIRTIME !!!!!!!!!!!!!!!

I have been a customer for many years and the service just gets worse by the day! My data contract came to an end on the 31 July 2017. I called in May 2017 and again on the 19 June 2017 to give notice to cancel. The consultant then tries to retain my custom by selling me 20GB for half the price I was originally paying - I fall hook line and sinker. Data DISSAPEARS - this is besides the fact that at the end of Aug 2017 - they charge me for the new wifi package PLUS the cancelled one!!!!!!!!! I call to have it reversed ref : ********** ********** 2 weeks ago - STILL NO FEEDBACK- I have tried calling every day to no avail " experiencing high call volumes" - no wonder why ! PAY BACK THE MONEY !!!!!!!!!!!!