HDFC Bank Bank Fastag — amount not credited to fastag a/c

Address:

Anantapur, Andhra Pradesh, 515001

I made an online recharge on 20th Nov, 2019 but the amount is still not credited to fastag A/C. Whenever I tried to call customer care I get a busy tone. I have the transaction Id. Now I doubt that this Fastag thing is not working fairly eventhough the Govt. has made it mandatory to collect all Tolls on Fastag from Dec 1st, 2019. I'm afraid to make further online recharges doubting that I just lose money on this. Please help!