Company cheating me of my salary by cooking up fake policies

My employer is not paying me my annual pay saying that they've decided to not pay inspite of being part of my offer letter following which I resigned to whjch they forced me to serve 90 days instead of 15 days notice period. They are not paying even paying leave enchashmment. On top of it, if I take the leave they reject it saying that it's a technical glitch, I actually have no leaves which is a lie, they only cheat by saying it's policy, although there is no such policy, neither in policy documents on online portal nor in offer letter neither communicated. In fact, they have asked me to work even my last working day threatening that they will not pay the earlier salary if I don't work and even the exit offboarding process hasn't been paid. On top of it, they are refusing to give offer letter. Even my approved leaves, now after leaving the organization, they have turned it to lop so that they don't have to pay in FNF, just cheating me. Everyday, they made me work overtime ,, 10 hrs 12