HellAtWork 5½ years ago, I would have been telling you 'report report, you have great evidence'. However, my experience is, now, that you can have all the evidence in the world, and if it is too inconvenient to deal with the real problem, they will take the path of least resistence.
I was working for a large Public Sector Organisation. As such, they have a very established 'whistle blowing policy'.
I was in a tricky position. My line manager was the partner of my same-grade colleague. But, my same-grade colleague was...taking advantage....of that position, and cherry-picking shifts, refusing to do certain work, and the result was that despite her years of experience, I as a newly qualified staff member was having to do more of that work, and at the same time supervise an unqualified member of staff, while she was able to insist that she worked with our boss, so had support, rather than being a supporter. Added to that, was the fact that I realised our time sheets were being completed in an....unorthodox fashion...on instruction from our boss, so we were being overpaid. We had questioned it on several occasions, and been told this was legitimate - it wasn't.
When I challenged the colleague directly, the result was that a time-bomb went off. I was frequently shunned, excluded from team comraderie, other colleagues simply 'took cover' - can't blame them. I was increasingly moved to another section of work so that my colleague and my boss didn't have to share breathing space with me.
I couldn't stand it, the atmosphere was shockingly hostile, all because I had pointed out the unfairness of the working arrangements.
I found another job, and my boss wrote a reference, which was fine. However, on a future occasion, she refused to provide a reference at all, which effectively blocked my employment as it is a professional role.
I blew the whistle prior to leaving, shared the whole story. The management didn't believe me at first, then I basically had to say "how many people of this grade do you know who earn £x per year. How do you think I earn that much?" They then thought that I was simply worried that they would claw it back. I wasn't. I had genuinely claimed what I was assured was the right amount on claim forms, but I had found out that it was wrong.
I have since gone on to have 3 children, and my eldest has SN. I haven't been able to work for a while, because of her needs. The funny thing is that I was good at that job. Really good. I skilled up quickly, built relationships between departments that had previously been strained. I spoke to the department head a few months ago when I bumped into him, and he urged me to get in contact and do some agency for them.
But nothing has changed. The staffing is still the same (well, most people have moved on and there is a whole lot of agency, but the core is the same). The senior management knew the issue was too big, so they ducked.
I feel for you, it is a terrible, terrible situation. But my experience is that unless you set a watertight case that cannot be ignored, then ignore it they will, because it is too much aggro to deal with it.