Stm Company, Aurangabad, Maharashtra — they are doing fraud and trying to took the money from the people

I have taken the work from stm solutions to fill 1500 forms in 10 days. But i didn’t complete my work due to some personal problems. They called and asked to pay the amount mentioned in the agreement. I said ok i will pay the amount. I paid 4500. After making the payment they called me asked are you willing to continue this work, i said no. Then ask me to pay 26000 for agreement cancellation, i asked why should i pay you didn’t mention this in agreement you just mention only 4500 and now asking this much amount. They said you should pay if you don’t pay we will send you a legal notice. I said if i want to continue this what can i do they said if you want continue also you should pay the 26000. They are frauding the people. So please get me the solution as soon as possible