first the contents of your agreement needs to be looked into.
1. Keep your profit and loss ccount, balance sheet and bank statements ready to show hw much you are earning and your expenses.
2. you need to show your track record of earlier payments made to the Tata Motors.
3. If you have paid by cheque to the agents, then show that also along with payment receipt, if any.
You may ask for extenion for time line by looking at your past performance and payment schedule.
Be cool and calm while presenting your facts and if possible hire a lawyer who could represnt you and tactfully handle the issue.
Advocate Rohit Dalmia