NATIONAL IMAGING SYSTEMS INC Threatening sending my account to collections Van nuys, California

I just got off the phone after a heated discussion with National Imaging Systems.  My APA dept sent me a past due bill from them indicating that I had not paid for a toner cartridge.  I was telephoned by a salesman from this company offering a trial cartridge at no charge.  I received an invoice a few months back and had called and told them it was sent to me at no charge.  I was told to disregard the invoice.  I have spoken to a couple of people from the company asking how I liked the product and at no time had anyone mentioned a cost or an invoice needing to be paid.  Now they are offering to give me 50% off.  No way.  Because I authorized the shipping of the product.  Yes I authorized a shipment of a no charge toner cartridge.  The packing slip has net 30 days on it.  So what.  30 days net of nothing is still nothing.  Supposedly when the "trial period" was up, I should have expected an invoice.  I was never informed of a tril period or a cost being involved.  We want you to try our product and compare to your product.  Nothing like a good telephone fight to get your blood racing on a Friday. I am reporting to BBB immediately and am NOT paying the invoice.