Don't buy from Freemans, you'll be sorry if you do

I have not been credited for a return that they acknowledged receipt of, which they now say is "missing". On 31 August I ordered 2 of the same item and was sent the wrong size. I returned both items in the same bag they were delivered in, which was collected by their courier on 4th September. On 7th Sept I received 2 emails confirming receipt of each item. On 8th September I received an email saying one item would be refunded, which it was on the 11th. On the 12th I asked what happened to the refund for the second item and to date I'm still waiting for an answer. They say my "claim" has to be "investigated", that the refund department is "backlogged", and I will "just have to wait". They won't give me any commitment that my "claim" will be agreed. They've taken my money, had their goods back, and still won't give me back my money. The Customer Service representative I spoke with today said "this happens all the time". I am disabled so I do all my shopping online, and I have never encountered anything like this before. Something is rotten at Freemans.