Benchmarking Salary- I need serious advice.

I joined my firm in 1999. I am not one for progression. Happy doing my admin job. I have a stressful family life with some caring involved I dont want to progress. Since i joined I have had a cost of living pay rise each year. Then in 2020 following a benchmarking exercise it stopped. I have not had a cost of living pay rise since. Having worked at the firm doing the same role for so long my salary is now much higher than the bencmark. They refuse for, competetive reasons , to even tell me how far off I am. So I have no idea. I have tried asking managers etc to find out but no joy. Am I being unreasonable thinking this is unfair. I work for a big firm who are very successful. I appreciate I now earn more than others doing the same role, but most move on within 2 or 3 years. I save the firm a lot of money in recruitment training etc. I dont expect a lot. But to have had no pay rise in 4 years. Is demoralising. I know i could find another job. But my life is not easy and my firm are flexible and I appreciate that. I have been told the only way to get more money is to work towards a promotion. But I just cant put that work in whilst caring for my parents as well. I was so happy I love my job, my cost of living pay rises from 1998 to 2020 averaged just under 3.5% a year. But 4 years with the significsnt cost of living increases, means my salary does not go as far, I feel so down. Am I being unreasonable thinking this is just unfair or do I just accept it. I either suck it up or leave.

Update Thanks for the feedback. Appreciate the responses its been helpful. I think i need to go to my employers and show what I add experience, training new people. I only have not moved a gradrs because i know the expecations and I wpuld rather do the job i do well and still have the time to care for my parents. Than move up but potentially do both badly. Or maybe I take the risk and see where it goes..... if it was not for my caring role I would 100% have moved on. My main issue is that they appear to have down graded my role or at least downgraded the salary tagged to my role. Otherwise I woulld still be getting at a cost of living pay rise, even if not every year there shpuld have been one by now.