iCloud, iCal and iPhone event confusion...

Once upon a time, I plugged my iPhone into my Mac via USB and everything synced relatively flawlessly.

Since iCloud I have had a number of problems which I have simply learned to live with but none so frustrating or annoying as this one.

I have a weekly appointment every Monday. It is in iCal as an event and I have two alarms for it, two hours before and an hour before.

The appointments clash with two public holidays and there will be no appointments on 26th December and 2nd January, so I'd like to delete these events so that I don't get the audible reminders. However, I cannot, since iOS5, edit events on my iPhone and for some reason, in iCal, whilst the appointments are there for every other Monday, for reasons unknown there are no appointments on these two dates - so I can't even edit or remove the events on my Mac.

Any ideas?