Bad service from the operations team

I was double charged at Pedro's Promenade mall WC on the 10 of April, the incident happened as follows. I paid with a gift card and the cashier assisting me wasn't sure if the transaction went through or not as the till tray didn't open nor generate the receipt and she swapped again without me thinking of checking the Ballance. Few days later when I wanted to use my gift card knowing the funds that should still be available the card kept on declining till I checked my transaction history then I saw the transaction from Pedro's went through I went to them on the 19th to quierry the incident I was then assistant by one of the friendly staff member who told the process that I had to email the card statement and send an email I did all that and later that day I received feedback from them stating they will get back to me between 2-5 working day. That period passed I followed up on the email no response the 2nd time and the 3rd. I went to the store I spoke to the manager she took my details promised a call back over a week ago and I still haven't heard anything from them. Yesterday the 15th I went to the branch again I spoke to the same lady manager she told me that she was told the matter is being handled by their ops team and they will contact me I informed her that I never heard any response from them I only received the acknowledgement of my query the 1st time. to my surprised one of the staff members mentioned that mine is still Fairly new as there are customers that are waiting for more than 2 month's for the similar thing. How do do double charge a customer and not notice when cashing up at the end of day that your takes for the day don't balance. No communication and no effort has been made by Pedro's Promenade mall Mitchell's and the worce part they are not even replying on my emails I have been sending them