Poor customer service - no communication

I bought a camp cot mattress online which said standard on the description, but when it arrived it was not a standard size camp cot mattress - it doesn't fit into a standard size cot. I then asked for it to be swapped to another mattress that also said standard on the website. They have since collected the mattress but just refuse to communicate with me regarding the new one I'm supposed to get. It's almost a week now and I'm still waiting. I emailed one of the customer service people on Monday, who has to date not responded to three of my follow emails I sent him. His name is Chuma Mbali.

Today I have decided that I no longer want the other mattress, I will buy one from somewhere else. The least they can do is reply to my emails or pick up the phone to update me.

I have sent a request for a refund, which I need today, I am not interested in explanations of having to wait for days for a reversal. They have my money and I don't have anything in return for it. Also, when I bought the mattress the payment went through immediately, so if they need to do and EFT into my account then that's what they need to do, today.

Reference on package - MDX 136 252 56 / S105 830 074