Almost a third of renters have contacted Threshold in the first quarter of this year over tenancy termination.
The housing charity is calling for commercial tenant rights to be extended to domestic renters.
It claims some landlords are abusing the legislation to hike up their rents.
Threshold Chief Executive John-Mark McCafferty wants the Government to ensure the sale of properties are legitimate.
He said:
We are urging the Government to put resources in place to fully enforce the current existing legislation which would ensure that all of the tenancy terminations which are triggered by the sale of property or the alleged sale of property are indeed legitimate.