Discrepancies in Settlement Fees

I received per email & per sms on Friday 26 June 2015 that my settlement fee is R8317.30. Subsequently i sold my phone and on 02 July i requested their details for me to pay in the settlement fee to cancel my contract. I was then informed the settlement fee is R9824.96. A difference of R1507.66. Don't forget the debit order for the number was deducted on 01 july 2015. I have the emails and sms's to proof the amounts. <br> <br> How can my settlement fee be higher now after the debit order. <br> Pieter<br>