What can I do against a person who is threatening me to file false FIR?

Hi, I have a business one of my customer took material from me and he has 6 invoice pending for payment but he refused to pay since 1.5 years, we are making request to make payment but he is refusing, so we finally went at his godown and took material of equivalent amount and making note by company (customers)manager, but than they made police complaint of theft against us and by using some influence in police they forced us to write a statement, that they don't have any dues with us and we apologies for our mistake ,we have returned all their material as it was but now they are threatening us of FIR, if we file a complain against them.