By Arezow Doost, CBS 11 News

ROCKWALL (CBSDFW.COM) – Patti Roach knows she can cut 45 minutes out of her commute from Rockwall if she takes the George Bush Turnpike.

She knew she’d have to pay extra, but she never though it would cost her so much. “126 tolls they want $2,551,” she points to an invoice for just one month.

Roach says she would have paid, but stopped getting bills from the North Texas Tollway Authority last July.  “Around the end of November I received a citation Texas Department of Public Safety saying there was a warrant for my arrest for unpaid tolls,” explains Roach.

After calling the agency Roach discovered she owed about $300 in tolls.  But add up all the penalties for unpaid bills over the last eight months and Roach owes the agency $17,911.

“Of course I can’t afford $17,911, I have a kid graduating this year, that’s college money,” says Roach.

The NTTA wouldn’t talk about the specifics of Roach’s case.  But CBS 11 wondered why did a few hundred dollars balloon into several thousand?

“That’s part of the collection process as it goes through it goes deeper into it it requires more mail more checking more cross referencing and it becomes more of an expensive process,” explains Michael Rey with NTTA.

Rey says they get a driver’s address from the license plate, cross-referencing information with the Texas Department of Motor Vehicles.

And if the mail is not returned Rey says, “We go on the assumption that it’s delivered to the address that’s good.”

Roach says she’s tried to pay what she originally owed, but the NTTA won’t accept any of her checks unless it’s the full amount.

“They are not interested in collecting the tolls, they want to collect the penalties,” says Roach.

The NTTA says they’re willing to work with Roach now and would only require her to pay 60% of what she owes.

If you find youself in this situation their advice is to contact them if you haven’t gotten any bills.  You can also check with the Texas DMV to make sure they have a correct address for you.