INCORRECT DEBIT ORDER DEDUCTION

I recently upgraded my cellphone contract prematurely and was moved from a R350 top-up to a 100 minute top-up package. However all was fine until the debit order was deducted this month (today) R1361.89. It seems that I have an open account now? How is that possible to agree to 100 minute top up and end up with a open contract??? It's not the first time I have had problems with Autopage - a few years ago I had a problem with a data account - I thought it would be better to give them the benefit of the doubt and continue my service with them. I wish I'd rather cancelled my contract!!!! PLEASE PEOPLE be on the look-out for Autopage - they are not honest business people. They are expensive with their calls, sms & mms services! Mostly rude people in all the shops, disorganized shops and call center people with no integrity.