Return policy a farce

I bought a Samsung phone. I had problems with it so I returned it 20 May. It is now 36 days later. In this time when I wanted to implement the "after 21 days from the date you logged your return, we'll be in touch to offer a credit/refund" policy the trouble really started. I was told it was going to be delivered to me. Then I was told it was delivered and the return was complete. I never received my device. Then I was told the courier still has it. Sounds like a delay tactic to get out of paying me a refund. In the meantime I have had to buy another device as I can't continue without one.