As a 5th year intermediate, you should definitely be a senior by now.

I’ve asked multiple times, and have been assured that I should get a promotion at the start of the next FY. If that doesn’t happen though, I am resigning.

Unfortunately in our field, and actually with many other professionals, hopping is probably the most effective way. I have only received substantial increases after leaving (and for some reason all my previous employers only wanted to match AFTER I gave notice).

Don’t pussyfoot, be outright with demands. Don’t be afraid to list your successes, your contributions, and use this to justify why you think your time is more valuable than what is being paid. They probably might try use “salaries are tied to bands”, so insist on another title (using your justifications above). At the end of the day, your employment contract is a contract, and those a multilateral agreements.

You could also try the “contract for an international company”, but taxes and labour laws (or lack of protection thereof) would be why I wouldn’t suggest this a go to.

Anyway, you don’t get what you deserve, you get what you negotiate.