Misled About Discount

I was offered 30% discount when I paid R490 x 3, which I did ( balance supposed to be credited). To my surprise I got a call offering me 20% if I paid R220. I told the lady who called me about the previous discount offer. She said she will investigate and will get back to me. To my surprise I received a threatening sms, saying I will be handed over if I don't pay. I feel that I have been misled, maybe to reach their targets.