wi-fi connectivity

Newbie here. My MacBookPro sometimes has a good signal from the house wi-fi, other times impossible to connect to internet. Sometimes a good signal and it STILL won't connect. Sometimes drops me from internet in the middle of something. Tried various tests- restarting house Link-Sys, another test where I sat next to friend with similar MacBook at a cafe. His picked up store's wi-fi signal, mine wouldn't. Apple Store Genius Bar blames local provider. Local provider says if it's sometimes OK, other times not, it's the (brand new) MacBookPro. Now Apple Store recommending I buy Airport Extreme, and says it won't interfere with Link-Sys others use. That seems my last hope before I use this laptop as a doorstop. Help? Thx.

It could be the aluminum in the MBP that is interfering with the signal. It's possible that this combined with a slightly less powerful signal may be causing your issue. You could try selecting a different network connection from the Airport icon in the menu bar, if there are any.