Lapsing my duty

[jen12128]

I dropped hours last year as a duty I wanted came up and I got it. I dropped from 39hrs to 32hrs but last summer the duty was lapsed and its going to be the same again this summer. I have worked for royal mail for 13 years and when this happens I go back to being a reserve and not know what im doing from 1 week to the next, sometimes I am even put on full time duties. I would never of dropped hours if I'd have known this was going to happen. I have spoken to my manager about it who said everybody was told that if we were going to do lapsing this was the duty that was going to be lapsed, but everyone was told when I was off sick. It was never put on the notice when the duty was advertised so I had no idea this would be happening until it happened. Has anybody got any advice on if this is right, thanks