HDFC Bank — hdfc fastag refund not has been received in 4 months

It is very much painful to explain that my fastag replacement request had been not completed in 3 months later i said to surrender and refund the amount it is almost 4 months of surrender fastag but refund i have not received
They provided me mail id which is also not working
Fastag. [protected]@installationglobal.com
Wallet[protected]
Customer i'd[protected]