Unfortunately, there's no good answer without using the "U" word in reference to your Exchange Server. Mainstream Support for Exchange 2003 ended 4/14/2009. Extended support is available from Microsoft until 4/8/2014, but the way ActiveSync functions was changed with the advent of Exchange 2007 and again with 2010. Apple simply had to keep up with things.
The BB generally doesn't sync directly with Exchange. They insert their service in the middle, which takes care of things like this.
You can not rollback to a previous version of iOS. There is no way to do so without voiding the warranty and forfieting your righs to service and support.