SERVICE DELIVERY HYPERIL

Hi there I purchased an item through Hyperli. I informed them that there was a problem with the item. They sent couriers to fetch said item. After 21 days j queried and was told that they would give me a voucher. I informed them that I do not want z voucher as I will not be buying by them again. They finally said they would pay my money back. No banking details were asked for. Queried them again. Then got message to ask for banking details. I was informed that it would take 5 to 7 working days to pay money back. Well I am still waiting. They don't answer emails. There are no telephone numbers to contact them. How does one proceed now.