Generally a s/w update isn't done upon request except to correct a customer reported or known issue. So, IMHO, I'd ask them to correct the drive-ability issue - I assume there were check control messages stored when they happened. And if it's s/w related they may go ahead and apply any and all updates that are available for your car. That said, if they have to do that it generally requires most of, if not an entire day! BTW, I've made it a habit to take a picture of any iDrive reports / alerts that pop up. Having my phone handy makes that real easy and as we all know, a picture is worth a thousand words!
My opinions are free - you'll get exactly what you pay for!
1998 Z3 2.8
"Seek and ye shall find" ... start with your owner's manual!