Drivers from as far away as Manchester say they have been wrongly fined for journeys on the Dartford Crossing they did not take.
Anne Marie Kenyon, a teacher from Bury in Greater Manchester was fined in April and June but told the BBC she had never used the crossing.
She said her number plate begins with the letters DV and the two fines were for vehicles with DY and then OV at the start.
Both her fines were successfully challenged and cancelled but she said it was “frustrating” to have to clear her name and she was worried it would happen again.
Another driver, Eleanor Vousden from Berkshire was charged for using the crossing on Christmas Eve when she knew she had been at home.
It happened after the Automatic Number Plate Recognition (ANPR) cameras wrongly identified her vehicles that had a similar number plate to the one that used the bridge.
She said the penalty charge showed a silver Honda Jazz whose number plate was only letter different to the silver Honda CRG she drives.
She told the BBC it made her wonder “how often such mistakes occur and whether people do bother to check, if they can't remember where they were”.
ANPR cameras are used to keep traffic flowing on the busy crossing which which was used by around 55 million drivers last year.
A National Highways spokesperson said: “In some cases, manual checks are needed to makesure crossing details are accurate. This can delay those crossings being visible on the website.
"However, customers can still pay for these crossings at any time up to midnight the following day, whether the crossing is visible online or not.
“The easiest option for customers is to pay every time and on time. We’ve made this easy by offering different ways to pay which suit everyone’s needs.
"We want to make paying as stress-free as possible and limit any additional admin for our customers.
“In a minority of circumstances, penalty charges are issued in error. Where this happens, the charge will be cancelled as soon as a customer contacts us to let us know they are not the registered keeper of the vehicle."
