Bunch of con artist

Few months ago received a call from Slik Consumables regarding cartridges. Placed an order to get them of our case because they phoned 4 -5 times a day. Received the package. Paid the invoice in the package. 2 Weeks ago received a call from them again. They did not send everything and will be sending the rest with no extra charged. Last week received a call stating we are owing them money. Told them what was told to me when i received the second call regarding the package. They dropped the call. Today received a call again from them stating we own them almost R4000 for cartridges. They are rude. I told them the same story long story short there was a lot of shouting and I already sent them back their stuff to the postal address because they do not even have a physical address on the invoice. I refuse to pay. Because i do not even want the stuff. They dropped the call. I am phoning a lawyer today...