No need call the school, just go to the administration office
and produce your IC. If you want to ask a schoolmate to collect it
for you, probably you'll have to write a letter of authorization.
It's a simple letter which goes....
To whom it may concern,
I, (your name),
IC, (S1234567X),
for some reason could not come to collect my result slip personally
and therefore authorize (your schoolmate's name), IC,
(S7654321Z), to
collect my GCE A Level results slip on my behalf.
Thank you.
sign off
full name