How to file a complaint about spam SMS/Call now?

Something awesome happened today. I was getting the tire on my bike replaced at a shop when I noticed this missed call.
I called back only to realize that it was a telemarketing company.
Nothing unusual until now.
The lady on the other side was extremely polite at first. Told me that she must have called me in the past. And I might have reported their number to the DND department. She asked me if I did anything like that.
I told her that I report all texts and calls from telemarketing companies as I am subscribed to DND. She went crazy after that. Literally begged me to take my complaint back. Would not listen to any reason. Apparently the number was very important to them or whatever. Eventually told her to find out a way for me to take my complaint back (which I do not think is possible in the first place).

Same thing happened to me this week. A lady called me up, apologised and since she spoke very nicely and almost pleaded with me I agreed and they provided me an email asking me to send them an NOC. I had finished writing an email, but thought of looking up the company name. It seems the company was doing well, but some of the employees had left a lot of bad review mentioning that the management found some ways of deducting money every month and not giving them full salary. Next day when the lady again calls me she tried to cross me, her attitude seemed slightly rude and I refused to withdraw my complaint and asked them not to call me again.

After porting to Airtel, getting way too many spam texts. I guess companies get their hands on ported numbers and make use of the seven day period. I have filed complaints though Airtel would reject them for obvious reasons.

There is a new app 'DND Services' by TRAI, I downloaded it recently and was going through the status of my complaints. In most cases the complaint status is "Subscriber Disconnected", but in some situations I get "Not promotional in nature" and "Opted Category". Just to clarify I am on DND0, now when I got in touch with my access provider vodafone, they said that I must have agreed to some terms and conditions while signing up for something that caused me to receive these communications. One of the sms I got was for buying designer dresses and jewellery, needless to say they still didnt help me.

it is still so complicated.