No amount of therapy has been able to fix “In Treatment” actress Dianne Wiest’s apartment troubles.

The stage and screen star — who most recently played a psychologist in the HBO series — claims her longtime Upper West Side landlord has been illegally charging her market rate for her West 78th Street pad for decades — currently $7,290 per month.

She claims in a lawsuit that the landlord was getting a tax break from the city, which meant it had to follow rent-stabilization rules and not charge market rents.

Wiest is part of a tenant group suing the owners of 229 West 78th Street to lower their rent and to recoup the money they claim West 79th LLC was illegally charging.

The 13-story, 100-unit building was getting a J-51 tax abatement from the city from 1993 to 2004. Yet the landlord told tenants their apartments could be deregulated anyway, the suit alleges.