No Response, Ignored, Refund Delay!

In March I placed an order for items and then when it was paid for, they came back and said that there was an error with the pricing on their website and that it was incorrect and that I would get a refund. This transaction took place 18/03, after back and forth as to why another gentleman I know got the item at that “error" in price, my bank details were requested before lockdown and it was sent. Then on the 25th I got an email saying that because the bank details hasn't received I will only be refunded after the lockdown, which now frustrated me because I had already sent my details to the person THREE TIMES before the lockdown. After emailing with no response, this is my 5th attempt to get URGENT feedback.

I received a refund BUT only partial payment. I am still missing another payment and no one is assisting me!