UPDATED 07/26/11 12:39 p.m.

CHICAGO (CBS) — A new survey suggests you’re probably paying too much for your smartphone’s data plan.

As WBBM Newsradio 780’s Bernie Tafoya reports, most people with smartphones have plans that charge anywhere from $30 to $80 per month for 2 gigabytes of data.

LISTEN: Newsradio 780′s Bernie Tafoya reports

But a survey by the Citizens Utility Board says most people don’t use anywhere near that, and wind up paying for data they never use.

The survey shows that 70 percent of the nearly 1,900 bills CUB analyzed over three years were bloated by $331 in wasted data allotments.

“What we’re finding is that the average smartphone user is using just about 500 megabytes a month, and you really don’t see any plans that are aimed at that sector, and that’s really what’s needed,” said CUB executive director David Kolata.

Verizon quit selling its unlimited data plans earlier this month, CUB said. Neither AT&T nor T-Mobile sells such plans, leaving Sprint as the only remaining company that does, CUB said.

Instead, Verizon now sells 2 gigabytes or more of data for $30 to $80 a month, CUB said.

CUB suggests the cell phone industry offer more varied data plans, including a 500 megabyte to 1 gigabyte option, a family plan so one family can share a data package, and rollover data for unused data amounts just like cell phone minutes.

CUB has also released a guide to cell phone data plans in order to help consumers.