WORK CALENDAR IS GLITCHING!

Hi experts, i need help! 

we use shared calendars with our work emails. each shared calendar is a different 'room' for our function centre. within this 'room' we book the client for the duration. 

randomly our entries ( appointments) reverting back, even if we have made changes to anything. it isnt saving attachments and in even some cases weeks of bookings are missing. this is a massive issue in the operation of our business. our Tech support cant seem to figure out what is going on and i cannot keep entering in appointments over and over again. its an absolute waste of resources. 

Is there something we can do? I have tried so many things. 

Thanks