HDFC Bank — no response from hdfc after paying the amount for fastag

Address:

Hyderabad, Telangana, 500019

Hi team,
I have applied hdfc fastag through online and made payment of 500. The reference number of the application is hfr01115342. And it informed i will get a mail but still no mail and no update and there is no way to communicate.

There is no way to contact hdfc fastag guys as the customer care number given is busy or not being attended.

And i am having hdfc account from last 6 years but this is the first time i am seeing some miscommunication from hdfc bank