I will try to make this short. My June 2013 MBA (purchased in December) suddenly started losing WiFi. If the unit goes to sleep or is turned off, I have to turn off WifI, turn on WiFi select the network and wait. This is uber frustrating. So, being awesome as Apple is, they replaced the WiFi card for me (in under a day!) and sent me on my way. The problem. Still. Exists. I have tried it on multiple networks at different locations, even in another part of the state, to no avail. All other WiFi products (all Apple) work fine in my home and elsewhere so i know it isn't my router or the like. Apple has requested I bring it in again on Tuesday so they can resolve this issue. Honestly, I don't know what else they can fix so should I insist on a replacement? An upgrade? Thoughts? Thanks for your input.