HDFC Bank — unable to get my fastag whitelisted since feb, 20

I have called hdfc fastag customer care more than 10 times and registered complaints regarding fastag blacklisted issue. But the issue is yet to be resolved. But every time i call, they say it will get resolved in 3 days but its been 5 months. Pathetic service.
Kindly look into it.
Complaint id - i0011022