How to transfer service bond

Dear sir, I am currently working as a Senior Section Engineer( Trainee ) in Southern Railway. Now I got an offer of appointment from Indian Bank ( Govt. of India undertaking ) as Probationary Officer, For which I have applied before joining in Railway. I want to resign from railway and join in Indian bank. But the railway authorities are not ready to give the resignation certificate until I refunding the cost of training. As per Railway Establishment Rule chapter XIV. (1410. Regarding the Refund of cost of training ) it is possible to transfer the bond in the event of their selection to other posts under the Central or State Govt. or in Public Sector undertaking / Autonomous Bodies wholly or substantially owned/financed /controlled by the Central Government or a State Govt. It was informed from Railway authorities that Indian Bank dose not belongs to the any of the above said category and showed their unwillingness to transfer the bond.Please advise me what should I do