over billed than what's due in a contract

Following my last report dated the 18/06/2015, I was contacted by mpho who have changed my intial contract and assured that he will monitor that I don't get billed over my r99 p/m. I was debited on the 16/07/2015 more than that amount. Please see to this once again and correct your system as this is the second report for the same query.