Failure to make return money after refund.

On 10 October I made an online purchase with Builders Warehouse. Due to the misleading and confusing online system they could not deliver my order. I requested a cancellation on 12 October. I requested a refund to my credit card. Then Builders informed me that due to a system problem they could not refund it to my credit card and that I had to submit a banking confirmation letter and my ID for them to refund it to my account. I duly did this. Then I received a letter stating that it will be returned to my credit card. It has now the 23rd of October and NO refund has been effected whatsoever. Either to my credit card or my bank account!!