Employee Agreement issue

I joined an IT company and signed for employee agreement for 18 months(After 4 months they asked me this) and signed for it as job descripttion stated as "Software Developer" after lack of projects they moved me to night shift job to provide support for "Data entry" kind of job. It was like 15 days night(Data entry kind) and 15 days day shift job( In Day shift they gave development job) now I want to leave after 14 months because they dint tell me about I have to work for night shift it was also not mentioned in the agreement form. And I don't know whether they can run that kind of offshore support job because they dint mention about it in my agreement and offer letter