HDFC Bank — Fastag not mapped

The mapping of fastag of my car no. mh 01 by 4531, has been pending since 10 th march 2021. (hbl no.[protected] dt 10th march 2021). Repeated phone calls to the official customer care no.[protected], has got me the same response - "We have a back end problem and your case has been escalated."
I heard this response for the first time on 12th March and was asked for 2 more working days for the fastag to be activated. I now don't recall how many times I have called the customer care number and am fedup of hearing the same story.
On 19th March I was promised a call back from the department, within 4 hours. This call finally came though on Sunday 28th March at about 330pm. One Mr. Sanjay had called and profusely apologised and promised that the tag will be activated by Wednesday 31st March, evening. Needless to say, it is not yet activated.
I again made a call on 2nd April around 115pm and was again assured a call back from Mr Sanjay or someone else in 4 hours. It is now approx 24 hours and still no phone call nor is my fastag activated.
I have already spent nearly Rs. 1000/- as penalty during my travel between 15th & 20th March.
Please help to get my fastag activated without any further delay.
This kind of inefficiency from hdfc is shocking.