National Highways Authority Of India [NHAI] — Toll fee over charged

On 11th Sept 2021 I travel frm shillong to guwahati and while going I was charged 80+80 in cash since I could not recharge my sbi fastag and while returning after around 1 hrs they charge me again 160 in cash plus I got the msg of Rs 80 deducted frm my fastag. So I paid total of Rs 400. Is it the correct charge taken frm me and moreover if balance was not there in fastag then why Rs 80 was deducted.pls resolve the matter