Sony Ericsson Xperia X10 : Having Low Voice Call Quality

I know this is nothing to do with the Android aspect of the Xperia X10 but was wondering what the rest of you thought of the voice call quality. The Wife and I both have one and when I call my friends on mine they say they can barely understand what I'm saying, when the Wife calls me on hers to my office land line I can barely understand what she is saying and to be honest calling each other on them is equally as bad. I'm going to test out both phones tonight with the wife using our home land line and see what she thinks... She's always had a mobile where I on the other hand wasn't interested in them until recently now they are more like a mobile office than just a phone. I'm never in a "bad" signal strength area when people tell me to speak up and I don't talk quietly anyway, they also tell me that as well as the muffled/distorted voice it's grainy and drops out frequently... Like someone is intermittently muting the mic, for example. I've had a ferret about the net and I'm drawing a blank, a few reviews say the voice call quality is poor/awful but than there are loads of others that say it's great. I love the phone and the rest of it is outstanding! I've stuck the Helix launcher on it, downloaded plenty apps for work (I'm a Software Engineer for Networked DVR's) including TFTP,FTP,SSH clients/servers, synchronized my calender and contacts with Gmail, ported all of my personal and work notes on to it, got a Dropbox set up, got a few gadgets to enable/disable the WiFi/APN/GPS as I need them so it doesn't chew up the battery... I literally almost couldn't be happier! I'm loathed to think that the one thing that doesn't actually work very well on this is in essence it's primary purpose and based on what I've read so far on the net I would say it's just my phone but as we have two doing the same thing it can't be. Does anyone else have a problem with the voice call audio quality or are there any known related hardware issues ?