Airtel — Do Not Call

I had been registered for DND from the beginning, and allows only calls/SMS of transactional service. However I keep getting messages and calls from unknown callers who claim to have got my number through digital marketing, and also SMS from various numbers/codes

Whenever I raise an issue with Airtel, they have few standard responses
1. the number belongs to another provider
2. The messages are of type service

I even tried to raise an appeal, stating that the SMS are not of type transactional, and transactions means that it should be OTP, balance, amount paid, ticket booked etc and not loan offers, property offers etc, but there is no stopping of these spam calls or SMS's