My iPhone 5S iCal is not syncing with my Macbook. Instead of syncing the most current calendar, it duplicates every change made. My calendar is a mess. UGH!!

When I sync my iPhone 5S with my MacBook it doesn't replace events with the most current version.With every change I make on my MacBook iCal the iPhone iCal duplicates every change. I can no longer tell which is the correct event as there are so many duplications. It's a mess 😟 It's also very frustrating. I've only had the phone for 5 months and there's been a few issues. 😟 😟

Help please - Apple Support has been unable to correct to date.