Refuse to provide Tax Invoice

I purchased a couch for my small business office from Mr Price Home online. We have requested an tax invoice from them as they don't supply you with one on delivery. They have refused to provide us an invoice stating that their policy is to only provide one to customers with a VAT number, which our small business does not have. When we objected they simply restated that this is their policy. This obviously has major implications as the couch is now not tax deductable. It is unacceptable. I expecta full refund for the couch and delivery so that I can purchase a tax deductable couch from another retailer as such a large expense cannot simply be written off. They also had the audacity to send us a recipt saying that our enquiry is resolved. DO NOT BUY FROM THEM IF YOU ARE A SMALL BUSINESS!!!!!