I actually ran into such issues, in particular with commercial websits. Some browsers I use do not work for my online transactions for instance - annoyingly the local bank I use for logging into my account as well. It is basically the bank hijacking my money and forcing me into using a specific browser (or, at the least, very few; they improved compatibility a bit in the last years, but there were more issues in the past here). It is just a reality of the situation that some websites don't work well on certain browsers.
Why don't you consider switching banks? In 2008 I had to switch bank for exactly this reason.