Four years ago Bob and Mary’s and their son used their Verizon Family Share plan to send 33 text messages, talk for 184 free minutes, and to download 1.13 gigabytes of data. The bill? $17,984.02.

The family has been fighting it ever since, but after Verizon lowered the bill by half they refused to budge any further and sent the bill to a collection agency.

So how did this happen? Apparently the family renewed their contract with Verizon but the “two year wireless promotional period allowing free downloads had expired,” and the family didn’t realize it. Meanwhile their son had been tethering his laptop to his cellphone.

After the monthly bill came, and Bob St. Germain got over his shock, he saw that his son had downloaded 816,000 kilobytes, a unit of data storage capacity, at a cost of $12,233.

St. Germain said he called Verizon to see if it was a mistake and got more bad news: His son had downloaded another 375,000 kilobytes of data at a cost of $5,600 that he would be charged for in his next bill.

“If there’s extreme activity on your account, they should let you know,’’ Bob St. Germain said, adding that Verizon should alert customers of big charges, as credit card companies do. “Nobody should get surprised like I did.’’

They tried complaining to the Public Utilities Department but they have no say over wireless accounts, since cellphones are regulated by the FCC. After that, the family filed with the AG’s office.

As far as we know the battle continues.

Family, Verizon far apart over nearly $18,000 phone bill [Boston Globe]

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