After calling for 3 days, finally got through just now and successfully booked a hotel.
The one I booked is Radisson Vancouver Airport which costs me only 850 including tax. Much cheaper than I thought it would be!!
I called using skype and sometimes it would disconnect after 3 hours so my little strategy is that I will press the number pad for a few times in order to stay on the line (not sure whether it is actually working LOL).
Anyway wish everyone good luck and be able to book the hotel ASAP
p.s. I asked the costs of other hotels and they are just for you guys' reference (All the prices are based on solo traveler)
Days Inn: 650 per night (not sure why a 2-star hotel can cost you an arm and a leg LOL)
Fairmont and Four Points: Around 450-500 per night
Westin Wall Centre: 525 per night