Reliance Mart — additional amount added in my bill

Address:

Anantapur, Anantapur, Andhra Pradesh

I purchased tide surf 4 kg pack and salesman told that 1 kg free for that pack. But when i saw the bill they added the 1 kg surf amount also. I tried to contact but they didn't pick up the phone. Please solve the problem. They displayed offeres buy 2 get 1 free, but they added three items in the bill. Where i have to contact. Please clarify in this issue.