...and a teller won't/can't do anything about it and this will change nothing. Maybe leave your keyboard for a second and understand how the world actually works.

Unless you have billions at a bank, I don't see why any bank would even consider changing how their website works because of a single customer. And, well, real billionaires probably don't care about not being able to use a website on Firefox.

Of course, real billionaires probably have staff members doing that work for them.

A single customer might not have any effect, but if many of them do the same, it could. Don't give up just because your individual contribution is negligible.

Half the banks in my country don’t even have a physical location. And the ones that do are just staffed with low paid service workers who neither care, nor have the ability to do anything about your complaint.

I assume it would go about as well as complaining to Comcast representatives in the famous South Park episode.

You would be surprised.

My bank calls me once every few months, if everything is ok, and if there are is something that is bothering me and could be improved, or if they can help with something. At first I thought it is some marketing program and some manager has to achieve some KPIs, but surprisingly, they did listen to suggestions (it took time, but they eventually did).

So you never know, if you never try.

I had to interact with several bank customer support departments and I'm surprised by experience you described. Are you a $$$-business customer or something?

The funny part is, that it is a personal account.

Business account is in different bank, and the communication there was much harder (obviously by someone not trained in communication and having to talk to me as unplanned part of their job). The fees are lower, though.

So it doesn't seem to be by the amount of $$$ on the account.

They will not care.