Gratis Store Won't Let Me Use My Coupon

I experienced a serious issue using a gift voucher at the Adıyaman Merkez Park AVM Gratis store. I contacted customer service beforehand to verify whether my gift voucher was valid in-store, and I was clearly informed that it was. However, when I went to the store, the staff refused to process the voucher, telling me I couldn't use it in-store. There were no restrictions or special conditions on the voucher or the information provided to me. The store staff simply stated, "You can't use it here," without providing any other justification. I demand a resolution to my grievance, the ability to use my gift voucher in-store, and an immediate and swift response. Furthermore, when I contacted customer service again, I received a response that said, "Our store says it's what it says." This approach undermines customer satisfaction.