Missing data on contract

I have a contract for data at Telkom ( ***). On 29/08/2015 I bought 20GB for R 899 with my debit card from the Woodlands Mall Telkom store. I bought another data package for R 1485 on my Telkom account soon after, which appears on my latest invoice. My data was finished much sooner than usual and after enquiring at Telkom Woodlands we saw that the amounts used were much smaller than the amounts I bought. I lodged a complaint on 29/9/2015 and was told I would have a response within 72 working hours (ref nr: ***5). I visited the store 4 times during the last month and every time I have to stand in line and wait for up to 45 minutes just to be told there is no answer yet. I spoke to the Manager named Agnes at Woodlands, who promised to phone me back with answers the next day. It is now 5 days later and she has never phoned me , neither does she answer her phone number she gave me. The call centre is useless as they keep me on hold for very long without giving any help. I am desperate for Telkom to give me the data and answer my queries and give me the service I was promised. I work from home and this effects my business very badly.