Outlawing the collection of data would be hard and is unlikely to work, but the fact that companies like AT&T are allowed to sell your data, as they did with OP's (where else would that unused phone number come from), is an angle new legislation can use.
The EU now already has a piece of legislation aimed at stifling these practices. The US and other economies just need to follow suit.
The private agents were armed with the latest available discounts (which you could find for yourself if you tried). But their skills made them particularly more successful than a typical front-line sales employee.
The catch? It wasn’t a scam, and they really were trying to get their targets to switch. It seems that AT&T was more willing to sell consumer data than the general public is aware of. Converting their targets to AT&T granted their agency access to additional data which they then to passed onto their clients. And the target gets a discount, too. Win-Win-Win? :)