Poor service, no print and still waiting for refun

I bought a Groupon voucher in July 2015 to have an A0 canvas printed. I submitted my image and the voucher and waited. I eventually followed up to be told that I'd submitted an older voucher (my mistake). Why didn't they phone me? I then submitted the right voucher.<br> Again after weeks I had to follow up. It seems that my order hadn't been processed but they asked me to wait another week. After a week I phoned back and was told to come and fetch it the next day. When I got there the print was so dark that all the detail was lost and the colours were wrong. They agreed and said that they'd been having problems with their printer. I was asked to wait until it was re-tuned. I phoned and emailed to find out when this would happen - no response. I eventually set up an appt with the manager on 9 Dec, but when I arrived at the correct time she had left the office. I asked for my money back and was told it would be paid the next day. Two weeks later and I'm still waiting. No-one answers the phone or the emails.