product available in market rs 550 but he taken from me 900

Location/place: bijainagar, distt. ajmer, rajasthan

Name of company/service: computer systems, kachara market, bijainagar, distt. ajmer, rajasthan pin 305624

i purchase quick heal antivirus pro 13 from shopkeeper he get from me rs 900 but this product available in market rs 550, but this pruduct print rate is rs. 999 what i do.