Takealot has the worst customer service

I bought a tablet about 3 weeks ago from takealot and I haven't received my proof of purchase. I have made numerous calls and emailed them but I am not getting any assistance. They keep on telling me to request it from the supplier which I did but I am getting no help. I don't understand how can they sell a product and deliver it to the customer but they can't issue out an invoice which I needed very urgently and can't get.