Some brokerage sold my data!

Today I received a call on my office number from +35924812890 (Bulgaria), where an indivudual speaking a very poor english, almost unintelligible, wanted me to open a new trading account.
What made me really scary was: how the hell they got my work number??? I’m almost paranoid to give my numbers and emails around, I don’t mix work and leisure, who gave it to him?
Usually, when I join something not extremely important I even write a fake number, which I take note on my password manager, so in the extremely remote event that I really need to get called, I just say that I changed mobile operator and I got a new phone number.
I asked who gave him my data, he said “you left your business card at a trading event” – absolutely impossible!!! I insisted on this, but he hung up, and if I call back the number a voice says the number is wrong..
Probably some broker employee got access to customer data and decided to sell them to black hat marketers for nice money…
I get goosebumps thinking how easily I sent my id card scans to the various brokerage companies that I tried in those years…