Poor service and unprofessionalsm

I went to Mellins Vaal Mall to upgrade my specs, at first the service was exceptional, until when I received a call from Mellins head office to give me a different amount I owed to that i was given at Vaal Mall, the lady that called promised to call me back and she did not. After a week i received a call from the office and i was given a third different amount, after i have complained ,i received a call from Vaal Mall saying i can pay the amount of R3800 instead of the R3 070 they initially gave me. I made a payment of a R1000 before their debit went off, just before monthend i was spoke to one lady who confirmed the amount outstanding was R2800, only to receive an SMS stating I owe R2900, I then made a payment on the 7th,a day after the debit order was supposed to go through, it is now the 19th and I have not received any calls from Mellins, as they keep telling me my payment has not reflected. I emailed Rochelle today at 13:36pm and she has not rep**** back to me. I am not quite satisfied with this kind of lack of professionalism from your staff, to put cherry on top, your complaints department promised to sort this out for me and has not even sent an SMS or an email updating me of the progress.