Sharing my phone number with someone

Today I got a please call me from a guy who said his name is Tshiamo Mahlangu, when I called him he said we are sharing the same phone number, I asked him how long has he been using the number, he said about 2 months now. I’ve been using this number for years I even don’t remember when I started using this phone number.

My biggest worry now is that sharing this phone number with someone else is risky because many of my online uses this to confirm verification and I might miss a lot of important calls because of my field of work

I buy airtime, I use the phone number for my calls and verifications. I want to know how is this happening and why should I stay with service provider that compromises my privacy.

•The phone number the complaint launched based is the reference number of this complaint

Thank you.