• Education and job contract problem

i have joined aeducation cum employment programme of a private bank where it takes 4yrs bond of service.they give loan for this education which will be repaid through employment which they give.i have completed this course and was placed n mumbai as a relationship officer i.e total sales which i sis not in begining of this programme.after trying to do that job but i was unable to sales and i talked to my HR for 1 month to change my profile but they did not change and branch manager was creating problems and misbehaving atlast i talked to HR once again to change my profile and location but they said NO,so i sent a mail about leaving job.now they are threatening me and harassing me for paying loan which they gave for education but they did not give any certificate.i am not financially able .when i need they did not give my degree.now they are saying ,they will file a case against me and police can arrest me.please help me..........as i am very helpless.please hor humanity please hel me .