Request for refund

I am writing to lodge a formal complaint regarding poor service and lack of resolution from both Shoprite and PayJustNow. I purchased a R100 voucher, but I never received it because it was sent to my old phone number, which I no longer have access to. I have already explained this situation to both parties. Shoprite advised me to contact PayJustNow for a refund, while PayJustNow is now referring me back to Shoprite. This back-and-forth has been extremely frustrating and unhelpful. As a customer, I should not be sent between companies without a proper solution.