blackberry bold 9790 working by itself

Dear All, my bb bold 9790 has decided that its touch screen rarely works after 3 weeks, and the the touch pad is about the only control i have. the cursor keeps operating by itself and very quickly is flying around the screen. this makes writing emails, texts or bbms virtually impossible. i ve rebooted with battery, and done an OS reboot thru my laptop. i ve not dropped it, got it wet or downloaded any apps.....any ideas PLEASE! also am based in thailand where the return / replace is not an option and repair they seem totally incompetant....:)