Unable to get ahold of anyone for 6 days

I bought a voucher for sushi last week Friday from Groupon in order for me to celebrate my Birthday on Saturday the 21st. I then called to make a reservation with the restaurant after purchasing the Groupon voucher but the person on the line said that all Saturday's were taken for people redeeming their vouchers but there could possibly have space if I was a walk in. I immediately, still on Friday, sent groupon a request to cancel and refund my voucher as I won't be using it, I would be out of the province for the remainder of the year, which they sent an auto reply that it should take about 24hours to come back to me. I have tried calling them on a daily but no one answers their phones on the two numbers I was able to locate.I am not happy