Fastag HDFC Bank — non receipt of fastag

Applied for fastag via hdfc fastag on 23/04 paid rs. 500. Got confirmation message on 05/05 paid another rs.300.
Riase a compaint with fastag customer service around 25/05 as i never ecieved the fastag, guy provided me with a tracking no. And upon tracking there was no onformation watsoever. So shared this with him and he also couldn't track it.. Promised me that someone senior will call me back within 24 hrs. Nobody called. Rraised this issue again around 10/06, same promise again.. Asked them to give me a complain no. Refused both time point blank that they don't log complaints.
Can someone please guide where to log a consumer complaint about them
Application id hfr128007