I'm from Poland and while I never experienced a robocall, I have to deal with telemarketers every now and then because someone somewhere shared my number agains

I'm from Poland and while I never experienced a robocall, I have to deal with telemarketers every now and then because someone somewhere shared my number against my will and while in theory the caller is obligated to disclosure how my number landed in its company database, they're often hanging up in second they're asked or pulling the "it was randomly selected" bullshit, and recently, after GDPR they're giving premium-rated phone numbers claiming that's how you can exclude your number from database which obviously doesn't work. While singing contract for fiber connection, I had to repeat few times that I want to opt-out almost losing nerves talking with agent saying that I'm really not interested having telemarketers clogging my phone even if that means I'll miss a chance to win something - because that's how she tried to advertise that. I could either allow those calls for 5 PLN less on my bill or opt-out for same amount added to it and I did choose the latter. Anyway, there are sites and apps which are trying to "rate" calling numbers and warn other people - most of the times they do good job.