A driver's car insurance was suspended due to a computer error that read the speed limit on 60mph roads as 20mph.
Connor Davies, 17, from Penrhyncoch, Ceredigion, said the black box monitor in his car started incorrectly triggering dangerous driving alerts.
Wales switched its default 30mph speed limits to 20mph on 17 September.
Sterling Insurance said it suspended Connor's cover for four days but has reinstated his policy and apologised for the "technical issue".
"It was very frustrating," Connor said, "like what I was saying wasn't the truth".
Connor's mum Angela was also getting the notifications and said she told him to "take it down a bit", thinking he was accelerating too quickly as a new driver, having only passed his test three weeks earlier.
"But Connor said 'I haven't been speeding'," she added.
Connor tried a different route on his nine-mile drive to work as an upholstery apprentice, but the "unacceptable driving" alerts kept pouring in.
Finally he took his dad in the car to show him that driving 32mph through a 40mph zone still resulted in a speed warning.
When the comprehensive part of his cover was suspended on Friday for all the speeding alerts, Connor took a day off work to call the company and try to find a solution.
Angela said her son was being "punished for something he hadn't done".
Sterling Insurance made Angela and her son go to the locations of his alleged speeding infractions and take pictures of the road signs next to a digital map on a phone.
Connor's sister, the model and social media influencer Jess Davies, even posted details of her little brother's dilemma to her 167,000 followers on X, formerly known as Twitter.
My little brother has a black box in his car and his insurance VOIDED his car policy yesterday for continuously speeding. But he had not. Turns out the black box company has BLANKETED 20mph zones across Wales, including roads that are 60mph 🤦♀️
— Jess Davies (@_JessicaDavies) November 4, 2023
Sterling Insurance admitted the error, saying in a statement: "The national database had changed the speed limit of a number of roads in his local area across the last four days and a technological issue meant it hadn't been updated on the Fluxscore app when the journey was completed.
"The information has now been updated, the driver's suspension has been lifted and we would like to apologise for any inconvenience caused."
The firm called it an "isolated incident", and said it had no further reports of customers in Wales being affected.