Changing price on the system

I went there today to buy LG sound system OK when I get there I did window shop then lucky enough I've saw what I like, I've asked for help then they did helped me but problem started when I'm supposed to make payment. The system on display was saying R4399 but when I pay it says R 4699 then I've asked the lady was assisting me that what going on with price, she said to me they have forgotten to remove the old price on the display then I've asked her who's fault is that with attitude she asked me I take it or I leave it😡😡