Poor customer service

On the 10th of March i upgraded online with Mtn as my cellphone contract was due for an upgrade and today is the 20th of March 2020 and still i haven't received my device, but this morning i received an sms from mtn notifying me of my new package and congratulating me on my new upgrade. i got hold of one of their consultants who advised me that the reason for the delay on the delivery of the new device might have been caused due to them not having stock. my argument was why wasn't i informed about all of this from the start and now i have lost all the minutes as well as the data which was on my sim card because the upgrade was initiated on my contract package.