Associated Supply Company, Inc. Poor Business Practice Internet

We were called multiple times by this company trying to sell us ink cartridges for our HP printer.  I was told that if I would just try the cartridges for a month I could return them if I didn't like them.  I finally agreed. We received the ink cartridges.  I didn't try them for a couple of weeks because I still had plenty of ink in my printer.  When one of the cartridges in my printer did need changing I put in one of their cartridges.  It worked but not as well as the HP.  A few days later one of the other colors needed replacing so my assistant put in one of the Associated Supply cartridges.  After she put it in she printed off a page that showed the levels of ink in all the cartridges and the two Associated Supply cartridges showed to be almost emply even though they were just put in.  I tried called Associated Supply several times and never was able to speak to a human.  I left messages and no one called me back.  Yesterday someone called to tell me that I needed to pay for the cartridges.  I told them I didn't want to keep them and explained why.  She told me that I would have to pay a restocking fee.  I told her that no one said anything to me about a restocking fee.  She said it was on the invoice.  I told her that any information on the invoice was not any information I had agreed to on the phone.  I asked her for an address to send the cartridges back and I immediately sent them back by UPS.  I'm holding my breath now because I have a feeling that they are going to harass me about the restocking fee or else they'll say they didn't receive the cartridges.  I wish I would have never done business with them.