No refund after 3 months

I ordered 2 Kings Size extra lenght sheets online. I only recieved one but was invoiced for two, they promised to credit... no credit thus far. After opening the one item, I found it to be the wrong size in the wrong packaging, package was correct, but when sheet was measured it was a queen size not a king size. After two phone calls, they collected the sheet and promised to credit. So up to date, I have no sheets and they have not yet credited my account. I have phoned and emailed on numerous occasions. Unacceptable.