MTN bad mouth their own personnel

According to two workers at MTN's customer services (135), the P20 light is a duel sim, so it's suppose to work. But according to the sales person and everybody higher up, it is not, meaning, the second sim slot is disabled. According to MTN I had to inform the sales person I want a Dual Sim phone. Why? If I ask for a P20 light, which IS a dual sim, WHY must I ask/inform them I want one? WHY will I think of that, especially if the previous phone I got from MTN is a dual sim of which BOTH sim slots work. So, if I did the transaction over the internet, how would I be able to inform the 'computer' that I want a dual sim? But now they penalise ME because I did not inform the sales persons a want a dual sim. And that is AFTER two customer care workers (at 135) CONFIRMED that the P20 is a dual sim and that both slots MUST work. When I informed the area manager, store manager, and the sales lady (on separate occasions) of this, they said those people does not have all the info, they will tell you anything, they are slow to take all the info and specifications in, you can learn them only so much. According to the area manager the sales person at the shop was suppose to give me copies of the my new upgrade contract, which she did not. And according to her the sales persons are suppose to inform the customers that MTN's phones can use only one sim on dual sim phones, but (according to her) they are so used to everyone knowing that it is how it work with the phones they sell, they don't inform them as they are suppose to. So, again, WHY would've I even think of asking/informing them I want a dual sim if the phone I ask for IS a dual sim. Now I'm *****ed for two years to sit with a phone I can't use to it's full capacity/potential and according to my needs. Their solution is that I carry around a router with my data sim (my second). I'm on a very tight budget. And MTN's data is more expensive than Vodacom. Now I'm forced to 'upgrade' my contract to one with more data. I have data! On my second sim! Which I want to put in my brand new, very nice Huawei P20 light, which IS a dual sim!