Please help, address rock werchter festival?? (urgent)

[koala]

Hi,

I live in Belgium and I'm going to Rock Werchter, a festival that you might know. It starts June 30 and I really want to write a letter to an artist there, because he's finally in my country. But does anyone know which address I should use? I've only found one and it says something like :

Festival Park
Haachtste Baan
....

But there is no number and I'm afraid my letter won't be delivered! I already asked the organisation several times, but they never sent back..

Can somebody please help me? I need the address by next Friday..

Thank you so much already!