Takeing my Iphone for service. Please advise.

[Encanto]

Hello everyone. Well this is the issue: after numerous complaints of friends and love ones that claim of hearing their own echo when talking to me I finally decided to contact the AT&T Tech support. After doing a few tests they concluded that my devices(iphone) is having issues. I then, contacted apple and explain the issue. They told me that that its possible that there is something wrong with the iphone and that I need to take it in to Apple geniues Bar?(I think Thats that its called not sure) So, I am suppose to go see a tech guy tonight. I can hearing that when you get an exchange for warranties issues on your phone, they replace it for a refurbished one? Is that true? Also, I wanted to ask is if you guys have had similar issues regarding an echo on others persons end? (by the way please accept my apologiez if this have been discussed in another thread) Another thing I wanted to ask, is it normal when you type a web address or a simple text message that you get some kind of delay when pressing any letter on the keyboard? Does your iphone freeze frenquently? Thank you all for taking the time to read my post. By the way, I love my iphone. I think it has been one of the best decision I ever made.