Touchscreen glitch on my BlackBerry 9720

Today, while using my 9720, I started experiencing a major issue with the touchscreen. When the screen is switched on, the touchscreen works okay, except the top section (basically where one can access quick settings). After a while, the entire screen becomes unresponsive, however the trackpad remains perfectly fine. Then the screen starts mimicking input to the aforementioned top section, making the quick settings menu activate and deactivate automatically.

This also affects other apps such as Facebook and WhatsApp.

I have tried a battery pull and have switched the phone off and on a few times. I find that the longer the screen is switched off, the longer it takes for the screen to stop responding entirely.

Any suggestions on how to fix this?

You can reload the OS to try and eliminate any software glitches.... but it sounds hardware.

You can disassemble the phone and make sure the screen/digitize has a good connection.

At that point you have to consider is it worth replacing the screen?