Earlier quoted context omitted.
This is kind of kicking an open door but the guideline explicitly is to design your app ‘to solve a particular problem efficiently’
Problem: our customers don’t get exposed to our special offers often enough but they do spend time checking their bills. Let’s stop sending paper bills because ads on there are too easy to ignore and make a labyrinthine app where the bill can be eventually accessed if users know the menu cheat code which will change regularly. Did the guidelines mean you should solve a problem of the users or the company?
The problem is why is that company in the business of "special offers"? The job of the telecoms company should be to provide reliable phone/internet service and otherwise disappear in the shadows. There should be no reason to "engage" with them other than paying your bill or changing some settings, just like there's no reason to "engage" with your power, water company or trash collection company.