I would doubt that a company would give out their installer code, I know I would not. This is not to stifle competition, as I routinely will call in and reset our code to default or stop by and make the change for an account that has changed hands. With the installer code, you would be able to see the previous companies information, and with the proper inclination, you could sit right there in your home and cause a ton of mischief. Not that you would, but that information is held real close by most companies for fear of something like that happening. Odds are that they use that same installer code, in all of their installations as well, so if they gave you "your" code they would also be giving you the code to all of their customers.
I think your best best bet in your situation is to go ahead and request a service call and let a tech walk you through the programming if you desire that information. Right now, you are in the position of not knowing if you can get into programming or not, and if you go ahead and spend the money for a new keypad, it may be money down the drain.
The Honeywell(Ademco) panels are everywhere and I would imigine any reputable alarm dealer in your area will be able to service it for you.