As others have noted, Sony is a write-off when it comes to support or replacing the parts.

Here's a more direct link to the part in question, which is now only available for ordering on-line: 337-8001.

But that unit is quite fragile, and easily broken if the audio outlet is on the inside of the armrest. A better unit, available only in the US, is this one: 42-2495. As you can see from the picture, it's a true Y-cable, with right angle plugs, dramatically reducing the risk of breakage. They are also much better built.

I travel to the US frequently, so if people want some of these, let me know. If there's a demand, I'll pick up a bunch of them.