Role change without any increase in base salary

[Jobquestion]

I gave changed name for this due to specific details. But always find the career advice really useful here and have followed it myself in the past.
Long drawn out situation. I have been stuck in a role for over 5 years, no movement or progression and just general company inflationary pay rises. It's a big global company.
Last year, when my youngest startest preschool, I went from 4 to 5 days, gained new certification, made a huge effort as I had more energy and drive to progress as I felt stuck in a rut.
I passed exams which would allow me to move to a role with responsibility. I also achieved a top rating in the annual review. The line manager at the time said I should be on the next level up, I was a C and should be a D for instance. Anyway I chased and chased for about 9 months to see when the role would change and he gave me different excuses each time, HR were on it, should happen next month, etc, which went in and on with nothing happening. Eventually he progressed(!) to a new role. I explained all to new line manager. Same situation, I chased for another 6 months. In the meantime, two other colleagues moved from a C to D role, but not me. Eventually, about a month ago, my role officially changed to a D.
The Line Manager was congratulating me on this great achievement and mentioned the role came with a bonus.
I thought, great that was unexpected. But then discovered my salary is exactly the same as before. No change and a bonus is a variable thing dependant on company performance paid once a year.
Anyway, this bonus seems a disappointment in comparison to any salary increase. I guess my question is, is this normal for a role change to not get any salary increase? And why would a bonus be offered instead of a salary change?
After all of my effort and wait, it's such a disappointment and I am thinking of moving on as it appears to represent a lack of value in me.
I know I am underpaid compared to other team members when I know I carry more repsonibilty than them and take on more projects.
I work in IT, not sure if it's relevant.

In my workplace, it sounds like we have a similar type set up. Here you could go up a band but not receive a pay rise as you have moved up in increments in your current role, so you have already passed the entry salary for the next grade.
You would instead benefit from other changes from grade change like more hol days/bonus/higher yearly increments

I don't like it either btw!!!

That sounds crap OP. Even in my job if you are already above the base salary of the next band you would still receive a minimum 5% rise...unless that put you above the top of the new banding (which would be practically impossible). Have you / can you ask for a raise based on your new qualification?

I'm guessing the bonus is the least they can get away with as they don't pay pension entitlements based on it and it's not a set amount.
It's such a hollow victory after waiting so long. I'm actually angry when I send an email with new signature as it feels like a farce. I think I need to move for my own mental health at this stage.
Next step is updating my very outdated LinkedIn profile.

Sounds like you are unappreciated . Time to start job hunting . Good luck op

Yep, if you want to progress in your career moving periodically is the wise choice. Roughly every 2/3 years. Get applying and start talking to recruiters.

I'm in a very similar situation as you OP, except I am still waiting for official confirmation of my new role (after 9 months so not as long as you!) and I know I won't get a salary increase as they are only awarded at a specific time once a year and my line manager has already indicated it is unlikely to happen at the next round.
I too am feeling very unvalued and am actively looking to move. I think it's realistically the only way forward and at least this way we already have a higher/better title before moving so more likely to get a better position and negotiate a higher salary.

I'm too comfortable, enjoy my job, have some great colleagues, which makes it harder, but I agree. We need to move, or else nothing will change. Also, I am noticing elements of having mates and possible political connections and some sexism here. Which is drawing me to go contracting for a while to avoid all that crap.
Really need to step away from feeling bitter, it's not like me at all.

Yes I'm very comfortable too, I have been with the company for a long time, my line manager is in a different country and I have a lot of freedom. But I am definitely realising there is a lot more to the bigger picture and it's time for a change!