OsCommerce - fix USPS shipping module

I have had the USPS shipping module installed in my OsCommerce-based online store for over a year. Recently, the USPS seems to have changed their API, and now the module is not working properly. (Customers who have selected "first-class mail" or "priority" are automatically charged "express".) I need someone who will update/fix the shipping module as soon as possible, so that customers can select any shipping option and be charged the correct amount. This is VERY URGENT. Preferably someone who can fix it in a day or two. Thanks!