Cancelation issues

Spoke with an agent on January 29th to cancel service, canceled service for February 4th , billing cycle ended February 9th so I was due a return of $25, agent informed me i would not be paying anything after the call the account reflected the $25 return amount few days later the account showed $178 bill amount..contacted customer support they informed me that  the system would correct account by February 15th, guaranteed me that it would be corrected, checked back February 15th bill still showed $178..spoke with agent and was told that I would have to pay the $178 to receive $200 rebate.. this was not what I was told by the agent over the phone or online customer service. If this issue is not corrected I will be filling a complaint with FTC