I went through Groupon as well, when I'd made my purchase. After all the horrible stuff I went through with this company, Groupon basically told me it was my problem and that because I'd used the voucher, I could not get it refunded. This was even though I'd had all the problems with the company that were still unresolved. I do notice though, that even when I'd informed Groupon about PrinterPix and all the negative reviews, they still continued to offer vouchers for that company. I guess the money in their pocket is worth more than making sure their customers are taken care of.

You have to contact Groupon directly, and send them proof of a crappy company. I have done so, and have yet to hear back.

https://www.groupon.com/merchant/blog/groupon-refund-policy