I know you posted this ages ago, but I'm having the same problem with my TZ3 and I was relieved to find someone with the same problem.
I know it's definately not my skills with the camera as my colleague has the same one (and the same "skills") and his pictures are much better quality than mine.
I actually bought my camera in May and have been hoping up to now that I find someting obvious that I was doing wrong, but I think now's the time to take action.
What I wanted to ask was did you get anywhere with the seller? or did you have to resort to Panasonic direct?
And - are you now happy with the repaired model because at the moment I just want a new camera.
I hope that you are still able to send me a reply.