Cancelled Order never credited to my account

I purchased goods online at the end of November 2021 for Xmas. I then realised that the item was going to reach me to late and I cancelled the online order and bought the item in-store. The website shows that my order was cancelled and I never received the item, yet it is now 6 months later and they have not credited the amount from my account. I have sent dozens of e-mails with proof and no one comes back to me, when I phone I simply get forwarded to someone else or get asked to go in store to resolve the query, How can I go in-store to sort out the query if it was an on-line order dispute? I will never recommend getting a game account or rcs account as neither of the have made the effort of assisting me. Over and above this i am now paying interest on a cancelled order as well.