National Highways Authority Of India [NHAI] — collection of toll although monthly charges paid

This is regarding the collection of toll at bael toll plaza. I had renewed the monthly payment of rs. 250 on 25.4.2018 and had been issued a receipt that it will be valid till 24.5.2018. However from 1.5.2018 i was again being charged from my paytm wallet everytime i crossed the toll. On asking why it was so, the reply was from 1.5.2018 the monthly plan was to be renewed every calender month. My contention is then why had they charged me for the full month on 25.4.2018.
The second issue is there is only one counter from where recharge for the fastag is to be done. Now when we are moving towards digitalization, why the same cannot be done online, thereby same saving on time for the commuters.