Unpaid Wages To Senior Executives In A Startup

There was a 75% pay cut during COVID with an agreement (over email no documents were signed) over email to pay a certain amount of money and company shares. but now the company has flatly refused to pay the amount when I have designed to resign after working for them for almost 9 months. What is the remedy I can push for. the fact that I am in a different city is also a challenge. They are also threatening to not give an experience certificate after employment. Also does lawyers in India work with % commission basis agreement of final settlement on such cases if I pursue the legal remedy. Also how much maximum time it can take. The company has also done similar things to others as well in past, so can we prove a pattern and also push for malafide intentions and jail terms if it goes at that level for company executives.