Dear,
As per CLRA 1970, any employee engaged for work in an organisation as a contract labour is eligible for Bonus. Bonus Act 1965 depicts it very clearly. Irrespective of any number of contractors change, the principle employer (i.e the organisation for whom you are working) is the sole responsible to get your bonus for the period when the closure of the contractor takes place.
Terminal benefits as per the CLRA 1970 is clear on the subject and you even have all rights to approach the labour commissioner on this issue. Central Government agency has to release the contractors money after assuring all the structures of pay components are paid to the contract labour.
Further for any query please feel free to mail me. I will quote with relevant acts for getting the benefits. I had a practical issue solved on this aspect.
Tks
Sathish