Sometime during the 12-day Mediterranean cruise she took in May, Maria Francis made a crucial mistake: She turned her cell phone on.

While the Sacramento, Calif. resident and her husband lounged in the sun, her phone synced to the cruise ship's cell tower and instantly started racking up data roaming charges––a whopping $2.49 per minute.

She came home to a $1,558 bill, and Verizon, her mobile provider, refused to budge.

“I was going to throw up," Francis told CBS13's Kurtis Ming. "How can this be?”

Though she stands by her claim that she never used her phone during her vacation, the problem is that just by leaving a phone on to charge, you could be incurring data roaming charges.

Luckily, Verizon has since agreed to drop the charges, but travel nightmares like this are easily preventable.

Turn data roaming off. There's no need to visit a store or call up your servicer to turn off data roaming while abroad. In your WiFi settings on your smartphone, disable the data roaming option. This will leave you free to use public and private WiFi without tapping into any cell phone servicers.

Buy a prepaid phone. If you're traveling for extended periods of time, it could be wise to buy a cheap, prepaid mobile phone in the country you're visiting. Cell carriers also sell prepaid mobile Wi-Fi cards for computers which can be used to access the web.

Know what you're up against. Visit your mobile carrier's website or speak to a representative in-store about your travel service options. For example, Verizon has a good trip planning tool lets customers know exactly what roaming charges they'll face and their alternative usage options.

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