Reducing contracted hours

[billintights]

Hi. I am a mail centre worker currently working a full 37 hour, 5-night night shift. Over a year ago I spoke informally with my shift manager about reducing the number of nights I work from 5 to 4, stating general health and family reasons. Because of alignment issues in the mail centre I was told no decision could be made at that time. I tried again a year later, this time submitting a formal written request, but received the same response with the strong hint that my request was unlikely to be granted.

Is there any other way to go about trying to arrange a reduction in hours, and must this always go through the shift manager? Could I go above him to the mail centre manager? Or could HR Services act on my behalf in arranging something?

Would appreciate any thoughts on this.