taking underwater pics

through my own fault I have managed to flood the UW case of my Tz18.  but the case also fits the tz 20 so i am wondering whether to get another tz18 (the pics were fab until the "incident" or upgrade to the tz20.

My concern however is the touch screen as clearly when its in its UW housing then i wont be able to touch the screen.

Can any one help?

Thx

Chris