2GB data per month but billed for 5GB

Hi,<br> I have had a 2GB data modem and laptop contract with Nashua for almost 2 years. It ends this month. I have been billed for 5,5 GB of data usage to the amount of R3600.00 where it has been R314 for the past 2 years per month. The money has been debited out of my account and has cause a huge inconvenience in my life. I have been booked off from work for being physically sick because no one can help me resolve this. The lad who helped me at Autopage said that my contract is not on file and it could take weeks to retrieve it. The contract states that I signed for a 2GB modem but have been billed ONLY this month for a ridiculous 5,5 GB data usage. I have to pay for my studies and this money is now just gone due to a lack of records on your side. They have told me that they will refund me if they have the contract. I can not wait for this contract to be retrieved, I have never had problems with Nashua. If you look at my payment history you would see that something is wrong! You can not tell me I have uncapped internet if you do not have the contract to prove it. I need this resolved asap!