Homebuyers' moves are being delayed by upwards of six weeks by Sutton Council as it has failed to cover for staff sickness in a vital department.
Property experts warn the situation is causing people moving in the borough added stress and could end up costing them money - or even causing their moves to fall through.
Sutton Council carries out property searches when people move house to check that the property is not subject to any planning applications that could affect it.
Usually these searches take two weeks but, since the end of March, the process has been taking upwards of six weeks - leaving buyers in limbo while they wait to find when or if they can move.
Martin Humphries, director of Goodfellows estate agents, said his team, which works across Sutton and the surrounding areas, first became aware of the problem in April when some property searches had been delayed by a month.
Since then he has contacted the council about the issue and even Sutton MP Paul Burstow who said the issue is "very important" and vowed to write to council chief executive Niall Bolger.
But Mr Humphries said he has not heard anything from the council and fears the delays could cost customers dearly.
He said: "It's a real issue at the moment as the market is moving so quickly. The danger is that in the time a vendor is waiting they could see their neighbour's property go for more and decide they want more.
"It is a stressful time for people and this is adding to it. I'm not anti-council by any means, but this situation can't be allowed to continue."
Among those who has been affected is a woman, who asked not to be named, who is moving between two properties in the borough. The woman and her family had expected to move in May but have been told it will now be July.
She said: "The searches were applied for to facilitate a moving date by the end of May but because of this delay and the fact I have a June holiday booked the move will now not be until July.
"Obviously this inconveniences not only my family but also the other two parties involved in the chain."
A leaked email seen by the Sutton Guardian said a team leader in the department has been off work for surgery and the remaining staff are working to clear the backlog.
Sutton Council has been approached for comment but has not yet provided one.