On the contrary, you can vote to change your government, but the corporations get to do what they want with 0 accountability. If they have a pseudo-monopoly (like several large tech companies do today), you can "choose" to use them or miss out on basic life services.
The fact that these monopolies can exist is a failure of the government.
Some, like telecom companies, exist because they have ownership over a scarce resource (spectrum). I might argue that because of that scarcity, internet should be a function provided by the government and not private companies at all.
Others, like smartphone OS's (iOS vs Android), exist because they are years ahead of any competition, and then entrench themselves by using custom parts and protocols. In an ideal world, there would be an OS-agnostic language for developing mobile apps, just as web pages are (mostly) browser-agnostic. Likewise, as manufacturing parts gets cheaper hopefully it becomes easier for tech enthusiasts to build their own phones with an open source OS. The government should have a role to facilitate this outcome.
But yes, monopolies leave us helpless
This is all only an issue because technology is exploding right now and our government is not designed for the rapid changes in legislation necessary to keep up. Improved communication tools have enabled outsourcing and automation that now allows 1 person to do what was formerly 400 peoples' jobs. Data privacy has become a very sudden public concern when 4 years ago it was revealed people could use that data to swing an election. Professional media outlets are now suddenly competing with average-joes-angry-blog for views and most have needed to switch to low quality/high outrage just to survive.
You end up in a situation where the same system that would have worked 50 years ago suddenly doesn't work now. But the current wealth disparity is not irreversible.