Angry customer

I have experienced bad service from a company called Yellowsub. I made an online purchase of goods which were never delivered. I made a follow with the courier service company and when they tracked my shipment, it was picked up that there was a mixup with address when shipping was done and that the shipment was sent back to depot. I requested to have the shipment canceled. I wrote an email to yellowsub advising that I am canceling the order and would like a refund. I provided them with my bank details, and to date I have not been refunded. My first email requesting a refund was written on the 6th of December and when I phone the Manager, Nasir, he ignores my calls. His office tells me that they have escalated the matter to him as the manager, and that he tells them that he will refund my money, but still no refund. Nasir is *****, as a manager of this company called Yellowsub, he unprofessional and they rip people off.