contract cancellation

first week of November i decided to take out a contract with telkom mobile for an amount of R299.00, and a day after receiving the device i decided i no longer want the phone and it was collected the following day,boom to my suprise telkom decides to deduct a whole R372-00 from my account for what because i barely used this phone not to mention even the sim card and the device was return within the acceptable cooling period,this is really inconveniencing,when calling the call center iam advised not to reverse the debit order and wait for someone to call me like really?