Siddhivinayak snacks scam - badlapur west

Siddhivinayak snacks near badlapur west station

Selling juice at Rs. 15 with mrp. 10

It's not about paying just 5 Rs extra, the question is WHY ? I told him I won't pay but there were 2 3 people and they pressured me in paying 15, by saying "10 likha hai magar hum 15 mein bechenge"

What should be done ?