If you hauled the load in January and invoiced in January, you should have started serious collections efforts by the end of February. Certainly by March, you should have been calling the shipper to discuss their participation in getting you paid and consulting with a legal professional regarding further action. It is now the end of August, seven months after you invoiced this low life. Overdue invoices do not get paid by doing nothing. Either get serious about your collection issues, or resign yourself to work for free. Sorry to sound harsh, but after seven months it is more your fault that you haven’t been paid. It is your money…..go after it!