CBS Negative Option Billing company in RSA

2015.Telemarketer calls to sell some printer cartridges, as a reward for 10,we received a voucher.Seemed legit<br> JULY we received 2nd delivery,nothing ordered.On viewing the original ordered cartridges,stock levels would run out.Kept it and paid for it<br> AUG, finally got to the 2nd set of cartridges we noticed that the printer cartridges were incorrect and did not fit our machines.Called them,they said they would fix it<br> SEP We received a delivery which was to make up for the incorrect delivery of July.We accepted the delivery which had no invoice in it but with 20 cartridges<br> OCT get calls from them requesting money for the Sep delivery.We disagreed as we did not order it and they had made a mistake,a delivery that was paid for and not corrected.They would check and come back.Several calls happened in exact the same manner<br> NOV the same guy, seems to change his name and position every time he spoke,now threateningly and rudely requests payment and denied making mistakes<br> DEC argue till he says hes picking it up,pack cartridges Wrong and right to make up invoice with voucher (still here)<br> JAN he calls for money I put down phone. He then sends notice from his 'legal' dept threatening me