My client refuses to give c forms inspite of repeated follow-ups

My client refuses to give c forms inspite of repeated follow-ups, and sales tax authorities are sending notice for payment for non submission of c forms, how is it possible for me to pay for every defaulter. can someone give me a solution please
8th July 2016 From India, undefined

pl write to the customer if c form not given the debit note will be raised for differece of tax, and give time for 10days..
15th July 2016 From India, undefined