Sunday extra boxing ticket - what to do

TPN

I am in this situation where I just got given a games volunteer role and am working this Sunday and therefore not able to attend the boxing event at Excel centre (my family is going without me).
I was going to resale my spare ticket on the website but is has not been working!!! I call them and they are not able to take the tickets back over the phone and there is no box office where I can bring them over they also told me becase is less then 5 days to the event they may not take it back even if i make it to the website!! It is getting really annoying!!
The info is as follows:
1 ticket for Sunday August 5th boxing at Excel centre it comes with a free travel card and is costs me £50.00
Women's Fly Weight (51kg) Round of 16
Women's Light Weight (60kg) Round of 16
Women's Middle Weight (75kg) Round of 16 Session code: BX017 Sunday
05 August 2012
13:30-16:30
With Sunday approaching any ideas what else could I do??
thanks