defendant admits his signature on document but refused to read content of document

Such statements are most common in all bank cases, and courts deem that once the document is properly signed, the executant has read the same.  It is his duty to sign after reading and understanding, and his failure is not an excuse.

In response to your query,

It's a very common in India, people deny the knowledge of the terms and conditions of the document when the time comes to comply with them but signature in a document is not always necessary for any contract to be valid in India. 

The essential elements of a valid contract are set out in Section 10 of the ICA.

It is entered into by parties who are competent to contract;

It is entered into by parties as a result of their free will (i.e. valid proposal and acceptance);

It provides for mutual consideration between the parties;

It does not require the doing of any act which is forbidden by law.

If the above mentioned conditions are fulfilled then the your case will be in a strong position. 

Regards,

Aryan Raj