My boyfriend just received a confirmation SMS for his reservist on 5 November to 18 November but we're actually travelling to Melbourne (Air tickets bought in 14 June, Hotel book on 18 June.) from 7 November to 13 November. What should we do in cases like this?
Please help your helpless sis here

a guy who is responsible should be asking this question instead.
5-18 Nov is a high-key ICT. Notices for ICT for HK is issued 6 month before, so it is a big question mark why did your boyfriend had only just received.
Only if he can prove he did only just receive the notification, he can talk to his unit in requesting for deferment. Do take note is the time when notification was first issued, and not from the reminders notices. What I meant is this and I supposed this was what he has experienced -
1. First notice issued - 6 month prior to ICT and acknowledgment is required;
2. If no acknowledgment within 10 days - hardcopy SAF100 will be issued to his registered residential address;
3. Still no acknowledgment - normally a phone call will be made by the unit;
4. Final reminder notice - 2 month prior to ICT to remind NSmen on the upcoming ICT
Dear NSman's girlfriend.... based on the above steps taken by Mindef in ensuring every NSmen are aware on ICT, I see no reason why you will encounter such an issue unless he did it on purpose or sad to say, purely clueless.
Just to add-on. If he has not contacted his unit until the day of ICT, MPs will be assigned to his address to visit him. And if he has failed to update his residential address, it can result into a civil case.