Despite of single BU user is able to access all BU's

User have given only one Business Unit access in Manage Data Access for Users task. But user can see all business unit's data. This is very very critical that one user should not see other entities data. Only has access to one BU but still he has all the BU visible. This is only happening for Finance users.

Account payables Invoice supervisor , Account receivables specialist , Employee are assigned roles with BU and data reference set access are provided for single BU.

Please suggest