National Highways Authority Of India [NHAI] — fastag double deduction

It has been a regular probleem at nhai toll on yamunanagar ambala highway at milk majra. Every time it happens that fastag is not working or they say it is black list whereas few minutes earlier same fastag is being used on previous toll plazas & has sufficient balance.
In such cases i have to pay cash. After few hours i get a message & mail that fastag has been deducted for the same toll where i paid cash as it did not work at that point of time. It is all due to untrained personnel on toll plaza operations & slow network systems on the toll plaza.
It is happening regularly & no solution. I end up paying double each day thru cash & fastag both.

Pl let me know how do we get refund in such cases??
Thx

Amardeep.