How can I fix my Tomtom XL?

My device's touchscreen is reacting erratically. With the keyboard on screen I am getting the wrong letter whenever I type the letters Q, W, E, R, T, Y, A, S, D, F, G, Z, X, C, V, B AND "BACKSPACE". Basically it is the left half of the screen that is awry.

I would appreciate any help how I can fix this problem. Will it entail replacement of a part or re-aligning an internal part of the device?