Spar 2U not offering assistance in reimbur*****t of failed order that was paid for

Did an online purchase through their 2U app, confirmed the payment, paid for the items, when returning to the 2U app the order failed and was cancelled automatically. Money went off my Capitec account for the order that's not existing. Spar is not offering any assistance in providing me with a letter of authorisation for Capitec to refund me for the failed purchase even though I have the proof of payment to them. At this stage it's blame shifting between the two parties and no reimbur*****t towards me.