|My wife also has a samsung galaxy gio, and it connects wireless with no problems.|
Just to confirm, it's connecting to the extender, correct?
It's unusual behavior for a wireless device to connect to a device with a weaker signal rather than the stronger. I'm not at all familiar with your device but if this were a laptop, I'd be able to force it to connect to whatever device I desired. Check your phone and see if you can't force it to connect. If you can, try and force it to connect to the extender.
Baring that, the only advice I can give you is to check with the manufacturer's support people. Perhaps there's a "feature" of the phone that needs to be tweaked, or a setting changed, in order to allow it to connect to the other wireless device.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.