Stamback Septic

I called stamback and told them I had a backed up water line and they sent a crew out but was not able to service me. They did not have the right equipment. My employee at the sight, called me to inform me they had left and was not coming back. I called another plumber and he cleared the renters line.
Two days later, stamback calls me for payment. Was shocked to say the least.
I asked the owner why, since I received no service from him nor did they have the correct equipment to take care of the problem. He still wanted payment. I received a bill from stamback on Thursday. I don't think I should have to pay his bill for not getting the job done.
Dave Perryman
*******@cox.net