Wrong pricing

I bought a table at SHF in Pietermaritzburg - THE PRICE ON THE TABLE SAID R1 990 TWL***4....so when I wanted to pay, I was told that's the wrong price on the table. The assistant went spoke Louise their manager called Chris Howells at Head Office . He refused to give me the price written on the table and said they should tell me it was a mistake. The actual price is R3190 and they should just give me 20% discount. That is unacceptable he knows it very well.