No sign of my refund after 2 months

I placed an online order on the 19th May and paid with my credit card. On the 9th June I checked the status of my order only to find that it was cancelled - I was not notified that the order had been cancelled and on quering it was told that the supplier was out of stock. I enquired about my refund and the voucher that I'd used only to be told it would reflect and was told it would happen that day - I followed up with another email on the 17th June and 8th July and to date I have had no reply. I have not received my refund nor have they reallocated my Voucher. THIS IS SHOCKING SERVICE.