I returned to work to find that my two peers had both been promoted a grade while I was on mat leave, leaving me the only one on the lowest grade in my area of work

When I had my first child, I hadn’t been at my company long enough to get maternity pay. When I had my second, I returned to work to find that my two peers had both been promoted a grade while I was on leave, leaving me the only one on the lowest grade in my area of work.
I then found my bonus was “pro-rata-ed” – in other words, halved, because of my leave. Apparently this is standard practice. This was bad enough, but the following year, still a grade below everyone else, my bonus was around half of the usual amount again.
I challenged this & was initially told I should “just try to work a bit more independently” and I might do better.
Eventually I called in my union rep and had a meeting with one of the senior managers, who claimed he’d just made a mistake and had based it on the previous year not realising it was for half a year.
It then took four months to get a written confirmation. I still haven’t had the extra money, and I’m still on the lowest grade.

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