Well that’s the difficult part.
I have friends who work for carriers who can’t get the problem addressed as they almost entirely run on number of complaints.
So the complaints of two experts pale compared to if 50% of those using the tower complain.
I am aware of one case where Apple corporate got directly involved, and even then it took months to see the issue resolved. Why? Despite market valuations, the carriers see Apple as “just” a vendor and its all about their financials and resolving some of these problems takes senior technicians and time.
A great example is one area that had issues like this crop up each Spring that went away each Fall, and it’s because that frequency was attenuated by the leaves on trees between the user and the tower; other frequencies were fine as they were not affected by foliage.
In short, the best option is to complain to your carrier, often if possible (“It’s been a month, it’s still an issue.”)
The good news, as it were, as more phones using the new frequency bands are released, the rate of complaints go up and it’s hard to blame “the new iPhones” when your customers with Samsung and Google devices are complaining too.