So if someone starts getting misidentified, or is erroneously put into a database somewhere and passed down the data brokerage systems, who does one petition to

So if someone starts getting misidentified, or is erroneously put into a database somewhere and passed down the data brokerage systems, who does one petition to be removed? With the government, you (usually) know where the data is. With private databases, who knows where it starts and ends? And once all major stores link up and you get banned from everything, how do you survive once you can't buy anything anymore?