Bankrupt Merchant Delivery Failure & Refund

I purchased a deal voucher in August 2015 & attempted to redeem the goods from the supplier print express during the course of September & they failed to deliver within the 4 week delivery time frame & extended the order completion to another month later. Thereafter, they yet agin failed to deliver on the said date & I contacted Groupon to request a refund for non delivery. This was December 2015 & they failed to refund me. I then followed up in January & again had to beg for my credit card to be refunded as they credited my account with them for some nonsense reason without my consent. Their supplier went bankrupt & couldn't deliver so it was only fair to refund the funds back to the client & not expect them to hold a credit. I called again this week to follow up on the refund & was advised that the funds were credited to my card only to have my bank advise that they cannot trace the credit which I was assured of was processed in February. This is ridiculous begging for money in a non delivery circumstance & having to call & mail them several times is quite frightening.<br>