Wendy Hill, who lives in Brentwood, travelled to Hornchurch on February 3 to take her grandson to a play date.
She found a space in Fentiman Way car park, before trying to pay at the ticket machine.
The grandmother claims the machine would not accept cash or card, forcing her to download the RingGo app, which she used to pay for her parking.
But later that day, she was contacted by Havering Council telling her that the ticket was invalid and slapping her with a £60 fine.
When she challenged the charge, the local authority admitted that she had paid to park – but claimed she had selected the wrong parking zone on the RingGo app.
A letter from the council said: “I have checked the RingGo system log, and this confirms no sessions booked for Fentiman Way car park.
“It does however show a session was booked that day for another zone in Hornchurch…Fentiman Way.”
It was then that Wendy realised she had mistakenly selected Fentiman Way as her parking location, instead of the car park.
“You can imagine – I’m in the car park and I’ve got a two-year-old that doesn’t want to stand still,” Wendy explained.
“He’s a very active child and there are cars coming into park, so I moved onto the pavement so that I was off of the road.
“The app gives you the option that it picks up your location, so I selected that and paid for the car.”
Wendy believes RingGo thought she was in Fentiman Way, rather than Fentiman Way car park because she had moved onto the pavement between the two parking areas to use the app.
In its letter denying her appeal, Havering Council described the Fentiman Way zone as being “some distance” from where the grandmother parked, despite the fact it is directly adjacent.
“I’m fuming because it was a genuine error,” she added. “It’s almost like its entrapment, they’re doing it to trap people.
“Even if the court ordered me to pay it, I would still refuse because it’s really unfair.”
A Havering Council spokesperson said: “The penalty charge notice was issued as the customer booked a parking session for on-street parking in Fentiman Way, but actually parked their vehicle in Fentiman Way car park, these are two different parking locations.
“A challenge was received from the customer, but rejected on the basis that an incorrect parking location had been paid for.”
