Non reply to intimation under sec 245, income tax act

Hello!!

There is a client who had recieved a notice under sec 245 of Income Tax Act to set off refund against a demand. He has received this intimation on various dates but has failed to act upon it. Now, he has approached with the intimation copy asking help to obtain full refund.

I would like to know - 

1. What are the consequences of not replying to the intimation under section 245?
2. Is there any possibility of getting back the entire refund?

Kindly guide.

Thanks & Regards

Anjali