Pathetic Service When The Company Is In The Wrong

Just pathetic service from this company,i called them in January to get my balance and was told one amount,then this month they debit the full amount yet my balance was only 20% of the monthly payment,i called yesterday and was told that only the agent who made the arrangement can close the account and was sent a letter confirming my account is paid up ,a note was made that the agent will call me back ..this was after 8am yesterday,so today i call back and get told the same thing …an email was sent to the agent to return my call and still nothing has been done ,i have contacted my bank to cancel the debit order going forward which comes at a charge,How long does it take for an agent to return a call ,i want my refund,i want my mandate cancelled.