When I accept a calendar invite iPhone 5 is sending multiple acceptance mails

Hi there,

I'm hoping someone can assist as I'm driivng my colleagues crazy.

Just moved over from an iPhone 4 to iPhone 5. Everything has been copied over ok and I was happy as Larry.

However I just got a meeting request from our works mail server (Exchange) which I accepted in the calendar app. The phone then proceeded to send 30odd acceptance messages to the invitee who just so happened to be my boss. I switched the phone off and sure enough the stopped only to resume once I switched the phone back on again.

I thought perhaps something didn't quite copy over correctly so I removed the exchange account completely and re-added it. I got a member of my staff to test with a new meeting request and exactly the same thing happend again. This time I just switched off the calendar and switched it back on which seems to have solved the problem of the multiple messages.

Obviously this not only mega annoying for the person getting spammed by my acceptance mails it's also killing my battery.

I wasn't having this issue on my iPhone 4 which was running iOS 6 so the only things that have changed is the phone and also the service provider. I'm sure former will blame the latter and the latter will blame the former.

Before I spend time on the phone to the network has anyone else experienced similar? And how did you resolve it?