Konkan Railway — charges levied are more than the printed rate

I am traveling in mangala lakhwadeep sf express from thrissur to nasik rd 12617
Boarding on 18th jan from thrissur
I bought a chips packet of rs.20 printed rate (Mrp)
And the vendor charged me rs.30
Last time i travelled in the train,
I bought a lunch worth rs.55 printed rate
For which the vendor charged rs.60

Now the problem is why are they charging extra amt. Than the printed one.
As its an excess amt, that too unrecorded that falls into black money
Why isn't action taken against such vendors???