Cell C unable to provide invoice for a website purchase

I bought a data bundle from Cell C. for my modem The transaction was done on the Cell C website with my Credit Card.

I want to claim the cost from my employer, since the data is used for work. My employer requested that I must provide them with an invoice of the purchase.

I contacted Cell C with their chat feature. The person told me to dail 084 140. I did only to be told to send an email to ********** so I did that. Received nothing back from them. [Incident: 181 ********** 06]. Decided to contact them again on 084 135. This person then told me that they are unable to provide me with any proof of this purchase and I should screenshot the SMS.

How is it impossible for Cell C to provide one with a prove of purchase for something bought on their website? Don't they keep track of the money that enters their account?