Refusal to refund after failure to deliver online order!

After placing an online order for items that builders showed as in stock they failed to deliver the items for 11 days. In that time I requested a refund twice and was told it will be processed back into my card but never done. Then 11 days later the branch decided to deliver and I requested items to be collected as they are no longer needed. Again a refund was requested back into the card used yet they decided to make it store credit and then told me if I want my money I will have to go in store to request it. I had complained again and then was told they will rectify it. 3 weeks later after providing they email today to ask me for proof of payment yet this was an online order which was paid for on the website. It seems your team is making it intentionally impossible to get my money back. Worst customer service! Please have someone who knows what they are doing contact me tomorrow.