Consultants sell you things you don't need because they do not know products (phones) they sell

Upgraded my contract and system would not allow consultant to upgrade me on the same package I have been for for the past 10 plus years so instead I had to be upgraded to a normal package (previously had consumer business package). The consultant also was not aware that the upgrade came with a free clear view cover and s-pen. This even though the current promotions and brochure clearly shows this so if I had not pointed it out I would have lost out on this feature of the package. Furthermore, consultant did not inform me that the phone had a pre-installed screen protector an sold me a screen protector at a cost of R499 (money down the drain as I installed it and the screen would not work properly so had to remove it again which, after some research as to why, I found that the phone already had a pre-installed screen protector). Why are consultants not trained in the phones and packages they are selling. Really disappointing service.