Homechoice is refusing to refund me

I purchased a brown Bentley Double/Double Bunk Bed from Homechoice on the 17 April 2018. I paid cash for the item. The Bentley Double/ Double Bunk Bed arrived in 2 boxes. We opened the top part of the 1 box and noticed that we received a white Bentley Double/Double Bunk Bed. I then requested a return because they delivered the incorrect colour. Two men from Homechoice came to collect the 2 boxes on the 4 May 2018 just before 7pm. I then followed up with Homechoice numerously on the returned item. I was told by a Homechoice customer care service consultant that only 1 box was received on their system at the warehouse. I have 8 witnesses in my house who were present when the boxes were collected by the 2 Homechoice men and who can confirm that both boxes were collected. We did not bother to open the boxes and assemble the Bentley Double/Double Bunk Bed, left it sealed in both boxes. I was told that the Bentley Double/Double Bunk Bed did not have to be assessed because the item was not opened, it was just scheduled for collection. I have requested a refund and I keep getting told only 1 box was received. I will not leave this.