Financially Prejudice by unexplained benefits

Took a contract on the 18/11/2017 for a P8 lite deal that was going for R179.00 per month, was advised that I will be getting 10 GB of data for the next 3 months me being a client thought it will be with effective as from November hence the billing in December will include November as well.5/12/2017 received invoice detailing that there was a R492.64 for data that was used up my question is how can 10GB of data deplete in 13 days I called the call centre where I was advised that the 10 GB of data will only be effective as from the 01/12/2017 and that was never explained to me cause if this was explained I would have managed this efficiently. I am sitting with a bill for R492.64 that I now need to pay for something that was not explained to me I do not work for Telkom and I do not know when is this available to me the consultant must disclose everything to me so that I do not have such problems or make an informed decision in handling my contract .I requested that my account to be capped for a reason Reagan advised me that I can only cap it effective as from 1/12/2017 the call centre has advised me that it can be capped from November had the right thing be done from the 18/11/2017 as per my request I wouldn't be in this predicament, I request that someone who can come up with a resolution give me a call urgently