Big Blue online shop a big mess.

I bought 2 items from the online store. I paid for both items. Several days after I had ordered them I received a call from Johannes at Big Blue to advise me that one of the items was not available. He asked if I would like a refund or credit voucher. I asked for the refund. This was the 20th July, 2022. two days later I received the one item with an invoice indicating both items were in the delivery. I reported this to Big Blue. I have still not received my refund which in desperation I asked to be changed to a credit voucher which I have not received either. Neither has anyone been in contact with me despite my emails , What's App messages and phone calls regarding this matter.