return to work

[tasjaybat]

I have recently returned to work from maternity leave, i filled in the flexible hours form as requested by my manager, he also insisted i email him with the hours and time i intend to work, i explained in my email to him that because i now have two young children both under 5 years i will not be able to continue with the hours i use to work, i explained that i certainly won't be able to work the late shift for now because my 10 months old baby is still breast feeding to which he agreed and sent me a signature confirming to all of this. i have only been back to work two weeks now and he has decided to change what was previously agreed by saying the shift i requested for doesn't exist, and that he has decided to say no to me working the hours he previously agreed for me to do. can he do that? i just find the whole thing confusing and unfair. could you advice please.thanks