Invocation of pledge

Hi

Please answer this query:

A Ltd. has pledged some shares of C ltd. worth Rs. 15000 with B for the loan of Rs. 10000 from B.

B has invoked the pledge.

we filed a case against B  to get the surplus of RS.5000 from him.

Now he is contesting that invokation is not valid. BCan anyone refer any case law related to this in our favour.

Regards

Hinna Garg