A woman said she was given "the fright of my life" when a "vindictive" police officer knocked on her door at night over her bad parking the previous day.
Sarah Lester, who lives alone, feared the worst for her family when police turned up at her house in Borehamwood, Hertfordshire, at 01:30 GMT.
She agreed she had parked badly earlier but was yet to receive a justification for the officer's early-hours visit.
Hertfordshire Police said Ms Lester's complaint was being investigated.
"I live alone and I didn't want to open the door," said Ms Lester, who was woken by the doorbell and her dog barking.
"I called 999 and they said 'it's a police car outside and you need to open the door'.
"I almost passed out, I thought something terrible had happened to one of my children; it was horrendous, I just froze."
'Nearly had heart attack'
The officer explained he wanted to talk about how she had parked her car in Bushey on 8 February, the previous evening.
She admitted her car had been parked partly on a pavement for just under two hours but it had been in her driveway since 22:30 GMT.
"I said, 'I've nearly had a heart attack, why didn't you put a ticket on the car or something in the post?', and he said, 'I've chosen to deal with it in this way'."
Ms Lester complained to police when the officer left but said she was yet to receive an apology or explanation.
"I feel it was vindictive - surely they can't do this," she added
"I haven't had a ticket, just this trauma from them."
A police spokesman said the Professional Standards Department was dealing with the complaint, the officer would be spoken to and Ms Lester would be updated "in due course".
"Due to the pending investigation it would be inappropriate for us to comment any further at this stage," he added.