thank you very much. Do i wait to be contacted by one of your staff members now or is there anything else i can do?

I have recently started recieving phone calls 4-5 times a day by FPC. I have also today recieved a letter saying i owe 191 pounds because of a debt i have with vodafone. I asked for a vodafone internet stick in September 2010 whilst i was moving and wanted a temporary solution for the internet was told the first month was free and then i could cancel the contract. I called vodafone and cancelled the contract and thought that was that. Apparently not though as i now have this debt and have no clue what else it could be since im not a customer. Is there anything i can do to get out of this? I am a student and dont have that kind of money to give, especially when i have done nothing wrong! thank you