R6313 for top up 1 Gig contract for R299.00

We signed up for 6 ipads 1 Gig Top up for R299.00 and 3 vodacom tablets @ R999.00 We have been over billed one top up account alone R6113.43 vs R299.00. We advised vodacom on several occasions dating back to October. I called, emailed. I finally got \We are currently investigating the below query you have brought to our attention. We are going through the communication and the orders you have sent through to Andre and checking on all services that has been activated. Once the investigation is complete we will amend an correct any incorrect orders and services that was billed and activated on your account."- this was the 19th Feb. My further calls and messages then went unanswered. We Called from an unknown number which sam answered then said would be resolved by the beginning of March"