Kelly Printing/Toner Cartridge / wrong product, cannot return

This girl called and said she has a toner cartridge that would last twice as long as our regular toner cartridge and would even make the drum last longer because of the finer toner in the cartridge. We were sent the wrong toner and now I am trying to return the product. The number they provided directs me to call a number that says it charges $3.79 for directory assistance. Not kelly printing at all. I now have a toner cartridge I cannot use nor return and after 30 days am supposed to get a bill for it. I was told that if we don't like the product we can return it within 30 days. Well, I have no way of knowing if it is a good product as it is the wrong one and I can not find a way to return it. Am I supposed to pay for something I can't use? If they call trying to collect, i'm going to let them have it.