Airtel — important banking sms not able to receive

Address: Thiruvananthapuram, Kerala, 695014

My airtel prepaid number fails to receive important otp sms from banks and other establishments as a result of which i have been unable to carry out any phone based transactions.
Bought a new phone on advice that the phone i was using might be faulty. But the problem remains the same.
The card has also been tried on other phones, and the same problem persists.
The service provider says sim is fine.
Very frustrating. Its been months now.
Please help urgently.
No. Is -[protected]