One of my abiding memories of academia is how truly appalling managers everyone seemed to be. Has your wife tried telling her line manager (if she has such a thing clearly defined) that she is finding the workload difficult? It could be that more senior staff have dumped stuff on her without actually considering what other stuff she has on.
Either that, or given the potential for viciousness in academic politics, maybe she is seen as a threat and is being overloaded to try and make her fail?
Her line manager is useless. And appealing to the head of department has achieved nothing. Essentially, you get what you're given and that's it.
She has lots of support amongst her peers (other lecturers), students and those in her field... but the University operates very much like a business and really does not care for the lecturers, just whether their REF ( http://www.ref.ac.uk/ ) targets are met.
Either that, or given the potential for viciousness in academic politics, maybe she is seen as a threat and is being overloaded to try and make her fail?