Yes, I think. There are rules around what changes can be made though. IIRC two important ones that seem to be common are only 1 free change, and any change must be made within x of customer being notified of the schedule change. I'm not sure what x is, I've been told 72 hours in the past but I know of some international changes being made much much later than this.

If the schedule change was very minor (eg 5 minutes) and doesn't cause a misconnect then you may be out of luck.