disputing the bill, services were off

I have a bill outstanding with rain , but I was not using the router because I didn't pay so no data was loaded it was switched off . when i took out this plan i was told it a month to month you pay you use , so what services are you charging me because i didn't use it, please go back to you calls listen to the sales agent and tell me where was i advised that i will be charge whether i use it or not , because if i new that i wouldn't have taken the plan, this is not a contract that i committed myself to pay every month, so the bill outstanding have to be paid by rain .