Breaking a Service Agreement

Hi, I have been employed in my current company for the past 1.5 yrs, however at the time of joining I was made to sign a service agreement (which was sent along with offer letter) and undertaking on a non-judicial stamp paper to pay the amount mentioned in the agreement upon breach of terms (mainly quitting before 3 yrs of service and without providing six months notice). May be I can cope up with the notice period condition but not the 3 yrs service, as the job is not upto my expectations and I am seriously troubled and highly dissatisfied. The amount they have mentioned is Rs 90000 training fee( 3 months) along with 1 yr gross salary. They haven't provided any breakup regarding the same.Also I was made to submit an undated cheque with the above total amount filled in it. In the name of training, they didn't provide something which I already didn't know, it basically included their work culture and all. I was already experienced in the field before joining the company nor was I sent anywhere abroad. Also they were collecting a certain part of my salary every month as a part of their fund, to be paid at exit when all terms full-filled. Now I want to leave the company for a better opportunity. Please tell me the legal action I could face and my chances of winning.