National Highways Authority Of India [NHAI] — excess toll fee collection at paranur toll plaza

Address:

603002

I stay in paranur, today 18 may i have used paranur toll plaza to visit chengalpet. Usually local pass is rs 30, but they charged my fasttag with 60 rupees. The same happed on 2nd may too. When i ask the guy in ticketing no reply.. Why i have been charged extra for local commute...
During my return i explained everything to the manager there then i have been charged 30 for return. But no answer for the excess fee received and also no refund for it.