I went through this EXACT thing with a major bed retailer - we bought a bed from the floor, inspected it at the time, but when it was delivered it had pen and texta marks, scratches etc.

Lonng long LONG story short - I got legal advice and found that if you are not happy with the condition of the merchandise, YOU are the one who determines the action necessary, NOT the retailer. Meaning that they can't say you can only have store credit, if you want a money back refund, that's what you get.

It took me MONTHS of emailing back and forth, and a couple of times I wanted to just give up, but once I found the above info, I emailed it to her, and said I would be pursuing legal action if she didn't authorise the refund within 7 business days. I got an email the next day saying something like, 'well we don't want to admit liability but to shut you up, here's your money back'

PM me if you need some help darl