Driving instructors claim their jobs have been made "impossible" by people hurling abuse at them and throwing eggs at their cars.
Teachers at the Driving Test Centre, in the Beaufort Park estate, off Aerodrome Road, Hendon, say the persistent attacks leave them humiliated and frustrated during lessons.
In one incident, they found what they believed to be human faeces left on a bench next to the test centre in Aviation Drive.
Ramesh Versani, who owns Monk School of Driving, said: "It makes us feel very undervalued and embarrassed.
"We are trying to teach people to be safe drivers but they are making it impossible for us. It has become a nightmare."
The instructors often bring their learners to the area to learn how to bay park in the spaces provided to them, but are banned from using them by those who live in the area.
As a result, St Georges London, which owns the block, has installed CCTV footage in the area to monitor the situation.
However, Diana Redmond-Mulrain, who owns Diane School of Driving, said: "It's so frustrating because we feel as though we are talking to a brick wall.
"I once had someone shouting at my car to move and when I asked them to stop doing that, he made me promise I wouldn't come back here. It can be quite frightening.
"I had the right to be using those bays at that time. They make it as uncomfortable as possible for us. It's off-putting and unsettling."
The bays belong to the Driving Standards Agency between the hours of 7am and 7pm Monday to Friday, and from 7am to 5.30pm on Saturdays. The centre was built four years ago but the instructors say the problems began sometime in the last year.
Deen Dureshi, who owns Deen School of Motoring, said: "They say we are a nuisance, but we are the ones who feel threatened.
"People have had eggs thrown at them and had their cars physically punched and kicked. It's not fair to make us live this way."
St George's London has also employed security guards to regularly patrol the area.
Retractable bollards will also be installed in early September to ensure the bays are only used by driving instructors during the specified hours.