BankFodder what does it mean, they are not alowed to putting it in to contract? Is that true?

Thanks a lot for Your answer, I will be looking for different kind of job, don't want to be someones slave just like that.

Hi guys, I would like to ask You about such thing, I'm working for some company , now I'm on probation period for 2 months more (6 at all) my contract contains "it is a condition of your contract of emplotment for overtime to be worked in order to meet customer requirements" , I'm working 4 on 4 off shift 12 hours each, but usually I don't have my 4 days off cause my employer always wants me to do overtimes saying like "you have to" not asking if I can, when I said I'm busy on last days off and can't do this 5 minutes later he came and said like "You are on probation period, if You would not do this overtimes You would not receive permanent contract" is that bullying? Do I have to do always overtimes for him? Looking forward for Your answers, thanks a lot.