My wife's iphone 4 doesn't see any Wifi networks when more than 4 or so metres away from my Time Capsule, and as such will not connect to my home network. It would normally see 2 networks, my neighbours and mine and always connected reliably and with strong signal.

Within that 4 metre range it intermittently picks up the name of my wifi network and will connect, but this is hit and miss. As a result she is chewing through the 3G data and this has to stop. If I hold the phone right next to the time capsule it will see the network right away and join it, but walking away from the time capsule sees the signal strength drop to the lowest bar after only 3 or 4 metres and then it drops and cant see it anymore.

This has recently occurred and although I cant be sure, it could related to either of these factors as they all happened about the same time
a) the screen and home button were replaced by a technician (local guys we found on Trademe) the other day.
b) the phone was dropped one days after we got the phone back form being repaired and now has another broken screen (don't get get me started on this! haha)
c) or perhaps it was due to the ios 7.02 update (I think my wife upgraded to that version only just recently)

I have other apple and non apple devices (phones and laptops) in the house and they are all working fine with wifi. I have tried these things so far but none have fixed the problem.
a) Reset network settings
b) Hard reset iphone
b) backup and restored the iphone

Anyone got any ideas on other software related fixes I could try? Is it possible the technician fella might have broken something related to the wifi antenna (is there such a thing?) when he was fixing the phone?