Some firms use the principal of making life at work downright unpleasant, in the hope the member(s) of staff will take the hint and jump before being pushed. A classic example is the usage of 'PIP's - most of the time unrelated to actual performance, just an HR approved tool to effect removal of staff.

A lot of the time conflicts arise due personality clashes rather than technical differences, basically your face no longer fits/the manager wants someone else in your place.

Best advice on those circumstances is to be polite, absolutely do the work asked, keep records of everything, look for a new job, but also retain an employment lawyer, so if they move onto stage two - aka "really fucking over the staff", you have options.

I have a colleague who followed this process in the UK, took them to tribunal, they bottled it, and settled when it became apparent how much evidence the staff had collected to support their position.