Incorrect items and no refund after 6 weeks

After telling me on the phone that they had stock, it took them 2 weeks to let me know my goods were ready for collection. But they supp**** the wrong item, of which I notified hem on the day I collected. It took them 3 weeks to decide that they couldn't provide the items I wanted, despite it being on their website. Then when I returned the incorrect items, it has now been over 6 weeks and still no sign of a refund, despite it being 'submitted to accounts' on 20 Feb already. I would not recommend them at all