Southern Railway — Parking charges Coimbatore

As per the board in Coimbatore railway station backside the parking charges are Rs 20 for first two hours but the contractor is making bill of Rs 30 when I told him about the same he charged me 25 but the point is they are cheating the normal public Nd harassing us. I had to argue for ten minutes. Kindly check Nd let me know if the tariff has been changed