Send them a cake invoice. Go to a bakery, have them decorate a cake just like your invoice, in red icing at the bottom "your invoice is past due, $10K due immed

Send them a cake invoice. Go to a bakery, have them decorate a cake just like your invoice, in red icing at the bottom "your invoice is past due, $10K due immediately". Have it sent to their receptionist. Everyone loves cake. The owner will be embarrassed as hell and pay up immediately if they can. The last thing they need is their employees wondering if they're solvent. If they still don't pay, send another cake invoice, but instead of putting frosting on a cake, put frosting on a cardboard box. I've had a friend use this three times. Two paid immediately. The third got the cardboard box invoice. All cheaper than an attorney. If that doesn't work, perhaps a singing telegram? Hope they pay you soon.