why can't you access your phone? is it because you cannot update to 8.2?
OR Apple still has it OR it cannot update and other things wrong?
I had a work 5S until May of last year when work pulled phones from users, so I reverted back to my iPhone 4 for 6 months (that felt like it lasted 2 years) and my home button didn't work 85% of the time, my battery was draining fast, and everything was slow.
I could have bought the 5S or something relatively cheap as places were making deals. I held off until the iPhone 6 came out and pre-ordered and got it first day.
IF, your phone is working just does't update to the latest OS and all else is "fine" I'd just hold out.
The iPhone 6 is definitely nice. a huge upgrade from iPhone 4. but from the 5S...both have slo-mo and TouchID. bigger screen is nice.
**sorry if this isn't too helpful.**
EDITED/UPDATED: I didn't realize you didn't send it to APPLE but an Apple-repair place. I'd suggest taking it to Apple Store. a scratched screen shouldn't deter them...unless the screen is popping off or the sides are dented and that interferes with the screen (since at that point they don't like to do much to the phone, not that it cannot be fixed)