A man was spotted on CCTV breaking into a number of cars in the middle of the night.
The footage shows the man attempting to open a number of car doors on Sunday, February 9.
Punam Halai, 34, from Grangetown, was one of those who had her car entered and said it left her feeling distressed, as it was one of a number of crimes in the area recently.
She said: "A lot of crime has been going in Grangetown lately. It was a nice place to live in and it still is but the people out there doing this, they don't care about anything.
"There was no smashed glass on the floor so it looks like he used an electronic device to break in as another car across the road from my house was also broken into as well.
"Luckily he wasn't able to take much. My sunglasses were taken and some loose change. A few months ago my father-in-law had his windows smashed and items stolen from his car too."
The sophisticated electronic devices which are often used to steal vehicles can be bought online and capture the signal sent out by car key fobs and keyless technology. The process is quick, and thieves can drive the vehicle away in a matter of a minutes.
Experts have now issued advice as to how to protect yourself from falling victim to the trick, including by storing fobs and keys away from doors.
Motorists with keyless cars are also urged to use old fashioned crook locks for steering wheels or gear sticks; to install a driveway parking post; or use a wheel clamp.
Punam admitted she was worried the same man would return to target other cars in the area.
She added: "When it happens to other people you don't realise how much it hurts until it happens to your own car or a family member's car.
"It's bound to happen again, if it's not to me then it will happen to someone else. People will do anything to get their hands on free things.
"Any of this technology that people use to break into cars should be banned."
A South Wales Police spokeswoman, said: "Cash, sunglasses and a USB stick were stolen from a car parked in Hafod Street during the early hours of February 9.
"A second car in Pentrebane Street was broken into the next day – cash and a mobile phone were stolen."
She added: "Being a victim of car crime is upsetting and an inconvenience. We would ask people to please remove all valuables from their vehicles when are unattended, and to consider leaving glove boxes open to show they are empty.
"Anyone with information on those responsible for these recent break-ins, is asked to please contact South Wales Police on 101 or Crimestoppers anonymously on 0800 555 111, quoting occurrence 2000049595."
