Refund of purchase to credit card

[Edge99]

I recently ordered an item online and purchased it on my credit card. The supplier took the funds immediately then messed me around for a month with no sign of the goods.

At that point I cancelled the order and they said they'd refund to the card - they still haven't done this and now tell me it'll be refunded by Wednesday.

My question is, I've no doubt accrued interest on this item on my card so do I have any right to charge it back to this company?