MTN Upgrade

I called in and made a cell phone upgrade on 8th of January 2020 and the phone was delivered today (16 January 2020) without a SIM card. I called in and asked how come I got a parcel without a SIM card and the lady said she wants to check she’ll call me back. When she calls me back she says that she can see that the system made and error hence I didn’t get the SIM card. I ask that the SIM card be delivered and she says that MTN doesn’t do SIM card deliveries, if they do it will be like adding on another contract OR I can go to an MTN shop but they’ll charge me OR I can return the phone and cancel the upgrade and do a new one. So I want to know how is it my fault that THEIR system made an error? Why should I pay for another sim? Why should I cancel my upgrade?