Bought some shorts online during Covid19, Shorts a...

Bought some shorts online during Covid19, Shorts arrived but were too small (& I ordered the same size M&S shorts as I was currently wearing!), returned the shorts, then was promised a 'e-voucher' via email! Well this seems beyond their capabilities, 5 emails later, 2 email addresses for them to use, every time checking junk folders, & another week gone by & still no refund! I don't have an account to retrieve the original voucher number, so looks like I've lost that money now, think I should go shout at a manager in the local store to get my money back? Useless Incompetent 1diots!