Airtel reads your private data - How sick!

Here is the series of events that happened...

1. My friend (say Santosh) used to stay in Hyd previously! I used to make calls to santosh often when he was there.
2. Three months back, santosh moved to Bangalore. Hence he got his Airtel mobile transferred to an Airtel Bangalore connection. So this migration was done at the cost of a change in number.
   
3. The Airtel Hyd ppl had some queries to santosh regarding his connection and they tried calling his Hyd no (which was eventually not present).
4. So now Airtel sweetly browses his Hyd connection call history and gets to find my number in the list and gives me a ring asking me to remind santosh to get back to them.
5. I initially thought Santosh should have given my number as an alternate contact number or something and informed the Airtel guy that he moved to Chennai. Also said will remind, once I see him.
6. I also asked Airtel, Don they have his transferred Bangalore number? He replied "no"!
7. Now is the ugly act two: The Airtel guy now calls Santosh directly and talks. Wait a sec. Did they look through my call logs on the server and guessed Santosh number?

I called up the person in Airtel (he was a Relationship Manager there) and asked "how did you get my number?" He said we went through the call log and got this number! I was shocked! Do you read call details like that? It should always happen with the concern of the client! Or at the worst case an FIR should be there to look into a clients private data! Asked him, if there is a disclaimer written for looking at such data? He said "no" again. After me asking many questions to him that he did not have an answer he said he will call me back! He did not get back to me, and if I ring back again he colleague picks the call and says he is not around!

So do they read just the call log or even evesdrop in the call when they are bored or browse some random sms and emails that flow across?

Is there something I can do about this breach?

Can I file a complaint some where?

P.S: The place and character name are fictional. But events along with Airtel are real!!