Sim swap, Potential ***** alert - why copy front and rear of a credit card for verification

My mother is visiting us, and mislaid the phone the morning prior to traveling here. We went to MTN Phalaborwa in order to do a sim swap.

First they asked for two methods of Identification (which is good), then made a photostat of her Id and the front of her credit card. I wrote on the Photostat "For MTN Sim Swap only 2017/12/15" as I do when any identity documents are being copied, in order to prevent *****, by making it unusable for any other transaction at MTN and other institutions(creating accounts, updating details, etc)

This was completely unacceptable to them and so I requested the manager (Cristina) to be called. She explained that it was company policy (erm, they did allow me to do it when I got a new contract previously) and eventually I said "Ok, let us just help my mother" so Christina herself made some Photostats again.

Unfortunately the phone was at one stage on a business account, so they could not complete the sim swap.

At this stage they handed the Photostats back to me and I realise that Christina made a copy of the id book, the front of the credit card, as well as the rear of the credit card - yes, the bit that contains the CVV number - allowing anyone with access to the Photostats, to be able to use the credit card details for *****.

Firstly, why does MTN not want me to write on a photostat, made by their own employee, to render it unusable for any other purpose than the intended purpose? please note, their own employee made the Photostat, we didn't bring our own copy that might have been tampered with.

secondly, why did the manager copy the rear of the credit card.

(btw, it used to be said that over 80% of ***** are committed internally - so don't give me any "MTN's employees are completely trustworthy" piece of BS. Companies with more stringent checks on employees got caught by their employees)

I will really be interested in hearing your answer - I have been a MTN customer for around 20 years now, and I will rather take the plunge an penalty now, than being a ***** victim of MTN's employees