I want my refund!

I had bought a Phillips airfryer from OneDayOnly in February this year. Early last month the airfryer displayed an error and would not work. I logged a return with them on 5 Sept and requested a refund. On 13 September, they collected the item for an assessment. On 29 September, without notification, I got a call from a driver from the courier company stating that they have my delivery. I was given an incorrect airfryer, smaller than the one I had originally purchased and returned. The item was collected again and since then I have been told that they are following up with their supplier and will get back to me. It's been more than a month with no proper feedback, no refund and no airfryer! Pathetic service!