Contract closed without no notice

It's been 25 days since my phone has been closed I can't make calls or receive calls last month on the 13th I paid the money I was told I owed and I asked the consultant to cancel my contract and make my line prepaid to avoid being charged further now they gonna tell me I owe I have to pay but I told the agent to cancel my contract I have probably 30gigs of data when it gets finished month end they won't reimburse me but they were quick to close my line I've been paying my line for 5 years never had this frustrating issue