Charging for removing a radio and arrogant staff

We just cancelled our contract that was month to month with National, they came to collect the radio portion of the system. i was given a form to sign stating that they collected the system. at the end of the month they deducted the monthly fee (happy with that portion) then they deducted an amount of over R360. So they phone me today after my email asking for a reason, this amount is for the collection of the radio no one told us about this. the lady over the phone was so arrogant and just said sorry and when i told her their customer service is bad she just said sorry again and put the phone down. NATIONAL SECURITY at no point did you inform me that you charge a crazy amount to have a radio removed!! your service over the period was terrible, and the lady that phoned me needs to learn some people s****s