We were supposed to be doing a story about a new phase in TransLink’s Compass Card rollout.

But while we were getting footage of me using my Compass Card on the fare gates at the Stadium SkyTrain Station, something funny happened – I was charged a $4.20 fare, even though I hadn’t left the station.

I phoned TransLink and asked what happened. A Compass Card operator blamed a “system error” and gave me a refund promptly.

TransLink has admitted to refunding $7,000 in the first week of November for over charges just like these. Mostly it’s people who tap onto the system when they start their trip on the SkyTrain, Seabus or West Coast Express, but forget to tap off.

By the logic of the Compass Card, that forgetfulness means you will get dinged the maximum three-zone fare of $4.20.

But NDP Transit Critic George Heyman believes that $7,000 is just the tip of the iceberg. He says it’s only the charges where customers have figured out they got “ripped off.”

“The system is already over budget. Now it’s going to pick the pockets of people who ride transit every day trying to make ends meet or to get to and from their appointments,” Heyman said.

“They put the onus on figuring out whether you’ve been ripped off on people themselves and then you have to make a phone call to get your money back. That’s not good enough."

If you look at another transit system that uses Compass contractor Cubic’s technology, Transport for London, reports there suggested as much as £64 million was overcharged by the system each year.

There, a new “contactless” system has a cap on the amount that can be billed. Our system, which was some $24 million over budget and years behind schedule, has yet to be fully operational, so it’s not clear how much money will be billed.

We asked TransLink exactly how my card could have been overcharged. The online record showed me tapping in and tapping out four times at Stadium Station between 9:25 and 9:36 a.m., and the system worked properly.

But the final tap in and tap out, I saw a line in my online history that said “115-RESERVED.” TransLink says that’s a shorthand for an indication that I didn’t tap in correctly.

That meant when I tapped out correctly, the system believed I had travelled from somewhere else, and billed me the maximum amount. That’s despite the system seeing me tap in at that station only two minutes before.

TransLink spokesperson Jennifer Morland says the agency is being forgiving with refunds. She hopes that riders will educate themselves on the system, and make fewer mistakes.

“We know this is a big change for our customers. That’s why we have taken a phase in approach. We’re doing everything we can to support our customers along the way,” she said.

Despite all this the Compass system has many advantages: being able to load your card from home electronically, and if you lose your card you can get a replacement without buying a new one. For TransLink, it gets data it can use to plan routes better.

It also allows riders to check where they travelled, and exactly how much they were billed.

It’s a feature I expect Compass users will have to use a lot.