I've never dealt with them, so can't help you with the company side of things.
However, assuming you used paypal, you should have 180 days to raise a dispute. I had to do that recently with a company, and lo and behold, they got back to me immediately.
Five months is still under the 180 days, so it may be worth looking into that route. If they respond you just close the dispute, but if you're unhappy with their response then you can escalate it and will probably get your money refunded.