Online Voucher Query

My workmates bought me an online voucher as a present for my new born baby on the 19th of May 2020.We went shopping at Edgars Northgate on the 3rd of June, where the voucher was transferred to a gift card by the cashier (Mpho) and upon redemption, we were advised that the voucher was already used.We were not given a clear explanation of how that happened and where.I have wasted so much time and energy calling the Edgars call centre where I spoke to Zizi who advised me that there was nothing that could be done to resolve my query.Upon insisting that there has to be some records when the transaction was done or where the items were delivered,she then advised me that she had escalated my query and gave me a ref number.I have received zero feedback since then. I have sent follow up emails and taken another trip to Edgars Northgate to get this resolved where the Cashier Nonkululeko called the call centre and spoke to Lelethu with no joy who promised to get back to me but still hasn't up to today. Can someone competent please look into this issue and give me a satisfactory explanation of how my voucher was redeemed where and how using whose profile? This level of service is beyond shocking and terrible.