Signed for an employment bond unknowingly.

Hi, I joined a private company on April 2nd. Agreed job is different from what they have mentioned. And more over they took a bond for period of 18 months, failing which I must pay 60% of salary. This bond agreement they have not mentioned during interview process. By then I have agreed to give my certificates for 3 months as they mentioned, but they gave me an acknowledgment for 6mths. After a week of joining they took signature on bond. During interview process they told that training will be given for initial 3 months. But no such training was given. On this month for 4 days one the resigning employee gave a brief on training for 2 hrs a day and finally they said to watch YouTube videos and learn. Now I am not satisfied with the work and there is no way of learning here. As I am in probation period I decided to quit the job. Anyhow I have took my original certificates back by giving some examination reason. I don't wish to pay bond amount. So how can I get away from this issue. And can I get the salary for the month of May for the period which I have worked.