If you haven’t already, go to an area that has lots of foreigners e.g. Sukhumvit. If you see other farrangs banking in the branch, you should have some luck. If you already tried there and without luck, you may need to go to Pattaya.
it can be a nightmare! I was in the same situation, you want to open a bank to show funds for visa but, banks make it as difficult as possible. Where are you based?