Not familiar with license/product keys even though you've dealt with many sims... That's odd, I have a cupboard full of games and sims and been a part of many many forums where this is SOP.
I don't know much about yahoo games, but if you somehow got a title somewhere without a proper license key, then you've most likely not got a legal version on your hands. You might even be aware of this, in which case the above would be very rude even.
But I would like to give you the benefit of the doubt, though.
If you have a decent and working install of the game, you should not lose any missions when you update the game. Perhaps your install was corrupted, and a fresh install might help.
Sometimes posts get overlooked in busy periods, and the SS06 board is not a busy place anymore. So if we done you wrong, then sorry, but we're only human, and volunteers, might I add.
But your attitude is uncalled for. If you can produce a license key, something that everyone with a legal copy should be able to do, you get acces to all the boards. And as such, in technical support your problem would have stood out much more, and might have been noticed.
So don't blame us for your failure to perform a simple task, please.
Cheers!
Fred