Overtime in lieu

hc2997

In February I earned over 30 hours overtime. I received a call from my manager on Sunday asking me to take my overtime in lieu to help the company survive for a bit with the coronavirus so I said yes. It was explained that after everything had calmed down I could take it in lieu afterwards. We then had a meeting 3 days later and was told different and that the hours in lieu had to be took before 1st April as everyone now has to take unpaid leave after then. I asked if I could get my overtime paid in this case and they said no it had already gone through pay roll. I am asking if there is anything I can do to get this money back, I have read online and to ask me to take hours in lieu, they needed to formally write something up for me to sign and to organise specifically when I would take this leave. Therefore, is it illegal what they have done? I was also not given much time to make the decision to take my hours in lieu and therefore feel like I have made the wrong decision. Any help regarding this would be greatly appreciated.