You can do a google search and you'll find plenty of companies out there that are willing to repair these phones for a nomial cost (commonly over $50), but in my opinion, if your phone is eligible for an upgrade, it may be cheaper to go that route. Most carriers have new and refrubished blackberries for under $100 (or even free) with a 2-year contract. For example, Verizon Wireless has the 8130 pearl for free when purchased through the web.
The only reason I suggest this is because you mentioned that your trackball and a key are not working on your phone, which could indicate that the circuit board is damaged (water, overuse, etc) and needs to be replaced. It is unlikely a software update can fix this (I've seen this issue with one of my users with a 8830 world phone).
Now if its just the trackball that is not working properly (scrolling in some directions), this is a common problem from use and can be repaired (see link below).