Double Debit and incorrect billing

Webafrica is my internet LTE-A service provider since October 2017. I encountered a problem with them on the 25/01/2018 where my 110gig data bundle had depleted and I needed to top up. I did an online topup of 20gig on the 25/01/18 at 21:05 which costed R200.00 through their website which took some time and received 2 invoices for the topup. I contacted Webafrica through their website on the 26/01/18 to dispute the duplicate invoice and the response from their agent stated that I have already used the data therefore they cannot reverse the charge. At the time only 1.5gig had been used so I do not understand how the data went over to the 2nd 20gig. Webafrica has debited my account for both invoices already. Last night I noticed that the entire 40gig shows depleted. I requested for webafirca to contact me as I was now gatvol. I was told that I must check all my updates etc as I could have used the entire 40 gigs between the 25/01/18 21:05 to the 28/01/18 21.00 which is ridiculous. Finalyy Rebecca Daniels from Webafrica said she will get the relevant departments to investigate and get back to me. I am disappointed with their service and billing system. I will not recommend the use of this service provider.