No refund on defective goods

I ordered an electronic toothbrush that was delivered on Friday 7 November 2015. But the brushes were not included in the packaging. On Monday 8 November 2015 I asked for it to be returned and for me to be refunded. The collection only happened on the 20 of November 2015! And I am still waiting for my refund although I have been told that it was made 10 of December 2015. I get no response to my enquiries and have requested the proof of payment. Needless to say, I did not receive either the proof of payment or the refund.