Letter of Continued interest-Imperial college London

I have been placed on the waiting list for MSc Management at Imperial Business School. I've been doing some reading online and it says to write a letter of 'continued interest' and to 'accept' my place on the waiting list. However, there is no mention of a letter of continued interest as a requirement or accepting a place on the waiting list. Should I still go ahead and send one? Will it increase my chances of getting accepted? I don't want to sound pushy to the university as well, but if such a letter is recommended I don't want to leave the chance.

Please help me out if you have any knowledge about this.