If you are in the middle of a contract, then cutting your wages is almost certainly a violation of your employment law rights. While I am by no means an expert on this matter, I did have a similar issue years ago - mid-contract wage cuts - and I hired an
employment attorney to fight the case on my behalf. It turned out that my employer was basically looking to scare people into taking the wage cut.
They got into some pretty serious legal trouble for their transgression, and nothing happened to me in terms of wage cuts after that. If you are between contracts, your employer can re-negotiate your salary, but as far as I am aware, if you are in an agreed-upon contract, they cannot just decide to reduce your salary. If you want to settle matters, contest this action with support from a legal professional.