Mobi money and 6 months flexi account.

Made payment towards my mobi money account to settle it and covered two installments for the 6 months flexi on the 25th of March, sent them a proof of payment but still payments are not allocated my bank account was even debited after making a payment but still I'm being told that my accounts are in arrears what happened to the payment that I made? I have been sending emails making follow-ups regarding the payments allocation but I have not received any response. All they do is harassing me with phone calls, what happened to payments being allocated within 24/48 hours? This is so frustrating and unacceptable.