HDFC Bank — fastag not received

Application Reference No. HFR850739

On 2nd December, I had applied for 3 fastags for my 3 vehicles, Two cars & 1 LMV. Payment of Rs.1600/- as demanded was paid from my Citibank Credit Card.
Vehicle numbers (1)car - GJ06KP1845 (2)car - GJ06LK5674 and (3)lmv - GJ06VV6673
I have received the Fastag for my 2Cars but have not received any confirmation or the Fastag for the (3) LMV vehicle GJ06VV6673 (Fastag still Pending).
HDFC Toll free number is useless which never gets connected and is permanently busy. There is no specific email to complain directly to HDFC Fastag department. We have to only wait endlessly without any information or file our complaint on this forum.
Request HDFC to expedite the process for issuing the Fastag and dispatch to our address as registered in our application.
Thanking you,
Yours sincerely,
Vishnu Patel.