How to withdraw case before getting File Number?

[hpjack]

Hi all,

I recently DIYed my CEC application and CIO received my application on May 21st, 2013 which is 1 month and 2 weeks from now.
Major important mistake was found in my application by myself last week and i would like to withdraw the case from CIO (which i suppose it is still at CIO cz i havent got my FN yet) before leaving any records in the CIC system.

Any of you know how to withdraw the case before FN is issued? can i still get full refund?

Thanks in advance.