Hi Thanks for the responses. I haven't been given detail as to how it has been calculated. I can relay the conversations that have been held between my managers and I. It would take me a while to dig out 3 years worth of weekly pay slips to be honest, to be able to accurately calculate. The frequency of me acting as manager is extremely irregular. I have been through periods of 3 months where i don't act as manager at all, and then 3 months where i do nothing but manage! It is very sporadic. To add a little more information on where the error was made, if that is relevant at all, my understanding is; Manager A – is my managers manager, and the person I report to when I am ‘acting manager’. Manager B – is my line manager – the person I report to when I am part-time and conducting my contracted role. Manager B reports into Manager A. Manager A asked me to complete a substitution form which covers the difference in pay between my role as a non-manager and my role as a manager. Manager B asked me to inform him how many hours different I worked each time I was managing (approx. 15 hours a week). Both managers submitted their information, however the form Manager A asked me to complete already included the extra hours. By entering an extra 15 hours each week I was managing, Manager B was overpaying me by this amount of hours. My main point, and the reason why i think i may have a case to fight, is that when I saw the increased salary – I was expecting it! I had no idea that i was being overpaid. Not only had I worked more hours, but I had worked at managers rates of pay. I had no idea that it had increased by too much – so I didn’t question it. They now want to remove my bonus payments as well as deducting from my weekly wage, but I’m sure It’s worth a fight – does the estoppel law back me up?? Or are there any other cases i can quote? Thanks

I am contractually employed for 25 hours per week. For the past 3 years I have been an acting manager. This means that I regularly find that i am being asked to 'Act Up', work as a manager instead of doing my contracted role. On the weeks that I am managing, I have an increased wage both due to level of responsibility, and also number of hours. I've recently been informed that on the weeks that i have been managing, i have been overpaid, and I now owe nearly £5000 which they are taking from my wages. Had I known that I was being overpaid, I would have contacted them, however I do not see how I was expected to know. Moving from part time to full time, and also working at a higher level, I would have expected a significant increase in my weekly wage. I could not have known how much this difference would be as they never informed me what the new rate would be. I'd be interested in hearing your thoughts on what, if any, rights i have to argue my case. A friend has suggested the Estoppel law but i'm struggling to understand how this would apply. Any help/advice would be appreciated.