National Highways Authority Of India [NHAI] — deduction of toll amount.

I was returning from banglore to tumkur on18/01/2019.in kulumepalya nelamangala toll at 11 pm as my vehicle reached the tollgate the person inside told that your vehicle fast tag is not scanning so please pay the amount. I payed 20rs amount. When i reached tumkur i say in icici fasttag 20rs amount deducted. So i payed twice in that toll plaza, one by fasttag and another by cash. So what should i do. To whom should i complaint.