Resignation and Bond amount to be paid..

Hello, I have done 18 months training at Central Academy for State Forest Services, after passing all the screening exams conducted by Forest Development Corporation of Maharashtra(FDCM). I was working as probationary officer for last 2 years. Before training I had to sign a bond saying that I have to serve for min 5yrs otherwise if I leave before that period, I will have to pay the training expenses to FDCM. I have resigned two months back, on my resignation they have asked to pay training expenses and one month's salary. I requested them to consider my service of two years against the training and proportionally relaxing the amount to be paid, but was denied by the authorities.The act mentioned in the bond does not exist, neither the name of Act nor the section i. e. Act and section of contract Act are not quoted in Bond whatever Act and sec are thr are totally wrong(for all candidates). Isn't that mean the bond is void? What am I supposed to do? Can they ask me for the interest on the amount payable, as I don't have money to pay at the instant..so can they add interest(as it is gov undertaking company) on that amount?