Screen issue

[marbii]

Hi.

I've been using arc for a month and have some small bugs.
first is all known wi fi issue, and second big one is screen issue. Screen is getting unresponsive in the middle, so some times I cant unlock phone or pick up a call. If this happens I have to press lock button and then it fixes.

I gave it to service but nothing have changed.

also sometimes mic and vibrating alert isnt working.

what do you think, this is software or hardware problem?