Two Toronto residents are cautioning Presto users to regularly check their transaction history after they were both mistakenly charged for a fare in Mississauga — a location more than 20 kilometres away from where they tapped on in Toronto just minutes before.

"So essentially, we got charged for using Mississauga transit but we were literally ... half an hour away from Mississauga," said Samson Solomon, who was erroneously charged again the following month.

When Solomon and his friend Ashley Howard contacted Presto, they were told that an investigation was needed to confirm they didn't actually board those buses in Mississauga. Nearly three months later, the investigation was still ongoing.

'It's just impossible'

Solomon and Howard were returning home from a trip to Costco on Aug. 22. Their transaction records show the two tapped their monthly Presto passes at 8:06 p.m. at Wilson station.

They then took the 52 Lawrence West bus home, but their records show that at 8:12 p.m., they tapped on at the Westwood Mall Bus loop at Morning Star Drive, more than 20 kilometres away from Wilson station.

"Based on the charges, we were somehow [going] from Wilson station to Westwood loop, which is in deep Mississauga North," Solomon said.

"It's just impossible."

Both Solomon and Howard were each charged an additional $3.10 by MiWay, Mississauga's transit system, which also uses the Presto payment system.

A screenshot of Samson Solomon's Presto account that shows he tapped on at Wilson station at 8:06 p.m., then tapped on at the Westwood Mall bus loop six minutes later. The stations are more than 20 kilometres apart. (Samson Solomon)

Solomon's records show the same thing happened to him again 10 days later. He was erroneously charged a MiWay fare, this time at a different location in Mississauga. He said Presto reversed that charge after he called to complain, but not the original charge in August.

On Tuesday, CBC News contacted Metrolinx and within hours, the regional transit authority said it was reversing the August charges on both Solomon's and Howard's cards.

Howard and Samson both were told that an investigation was required into whether they boarded a bus in Mississauga. (CBC News)

Solomon and Howard said they're speaking out to alert other Presto users to potential issues.

"It's more the principle," said Solomon.

"For someone else who needs that money, three months is a long time."

Metrolinx responds

Presto cards track your location through an electronic system that has a built-in GPS.

Metrolinx spokesperson Anne Marie Aikins said the machines are accurate for the most part but there are occasional issues.

"In a moving vehicle like the old streetcars, for example, or the new streetcars or buses it can be a challenge," said Aikins.

Metrolinx spokesperson Anne Marie Aikins said there are 'occasional' issues with built-in GPS systems and the information they feed to the Presto system. (Farrah Merali/CBC)

But she said Metrolinx "doesn't get many" complaints about charges at an incorrect location and that this isn't a widespread issue.

"Every once in a while ... it can go wonky like any other electronic system. And you can't really find an explanation of why it recorded that stop."

GPS errors

Transit advocate Steve Munro believes the GPS errors happen more often than people realize. He regularly analyzes data using the TTC's vehicle tracking system.

"I was looking at some vehicle tracking data [recently] and there was a bus that was in the Kawartha lakes and another in Mount Forest," said Munro.

Transit advocate Steve Munro says GPS errors are more common than people think. (Farrah Merali/CBC)

The problem arises, he said, if at the moment a user taps their card, the GPS is off. He said people with monthly passes loaded onto their Presto cards likely don't check their tap records because they're not charged for individual transactions. Munro believes with the expansion and integration of Presto into more areas, it could become more of a problem.

"As we start to have more people using Presto crossing between systems and we hear a lot about fare integration and one card to rule them all ... it's going to be very important that people get charged correctly for where they tap," said Munro.

Aikins said this past summer, Metrolinx brought in rules that allow for Presto to be used on TTC routes that cross city boundaries.

She said the move hasn't resulted in an increase in complaints since it was introduced.