It seems the online past activities can be viewed again up to 999 days in the past.
https://secure.ichotelsgroup.com/h/d...ransaction=999
If the numbers at the end of the link larger than 999, it will show the error message:
An error occurred.
We are sorry, our system is temporarily unavailable. Please try again or contact your nearest reservation office for assistance.
The number 900 and 1000 do not seem to work neither.
If it still doesn't work, try the number 365 (for 1 year activity).