National Highways Authority Of India [NHAI] — Extra charges for fastag by toll plaza

Hello,

On 25/02/2021, I did buy a fast tag from Sonapur Toll Plaza Assam.

They charged me Rs. 400 for fast recharge which was paid online and Rs. 400 extra for fasttag sticker.

On calling the customer service number of NHAI, they told me that the fasttag sticker is free of cost which means Toll plaza people have cheated me and took Rs. 400 extra.

Please look into this.