BAD ADVICE WHEN SIGNING CONTRACT

In Sept 2015, I received a bill for approx ZAR 6000 - alleged high usage on my data account (now closed -end of contract). My cellphone which has no query on it has now been suspended. <br> <br> I called the contact centre severally and went into the Sandton contact centre to query this in light of the fact that: <br> - On signing contract, I was advised that I was on a Top Up Contract<br> - MTN App provided to track usage indicates usage limit is ZAR 1500<br> - I did not receive a single high usage alert on the account despite consistently paying ZAR 279 over 2 yrs<br> <br> I was advised that: <br> - It is impossible for a limit to be set on the contract. Why then did MTN through its app advise of a ZAR 1500 usage limit? <br> - A number of sales consultants erroneously advise customers that they have a TopUp line. <br> <br> I feel backed into a corner - MTN claims verification challenge due to closed account (consultant closing the line was aware of query) but insist that despite it being unusual for this line, I must have used it. In the event that I did, I was provided information of a usage limit that I re**** upon and should not be penalised for their error and should not pay more than ZAR 1500 per month