Correct a bug in a php affiliate software

Hello, (Excuse me for my bad english) We have an Affiliate network software (like link share, Cj ...etc) Problem: Tracking system for leads and Clics works perfectly but not for sales and %of sales so you have to verify this problem and correct it . In Example: Normally , if admin set the % for sales to 10% , and a merchant set the Sale commission to 50$ , admin get 10% of these 50% (5$) , so merchant has to pay 55$ (5$ to admin and 50$ to affiliate) , But Now the problem is: affiliate get his commission (50$) but not admin (so merchant is debited only 50$ but not 55$). Please note : - 50$ to verify and correct this bug. - we accept only professionnel programmers . - as we are a confirmed french company, we need a legal invoice for this service (with your tax id...etc). - 24 hours to accomplish this job. Thanks