Can't Repair, can only re-install software

My Sony Xperia Z1, was having issues with using keyboard, when typing another letter around that letter is selected not one you intended, software sluggish, have to reboot to fix or it would reboot on it's own.<br> <br> Dec booked in @ Eastgate, then onto Advanced repair center, who just re-installed software & in process damaged power seal cover. <br> Had to re-book unit in a few days later to have cover fixed and issues that weren't resolved.<br> Received unit back after 2nd time, cover fixed but again all that was done was to re-install software, problem was back in a few days.<br> <br> 3rd time in I asked to escalate issues, called advance repairs, they were very sympathetic, lots of promises to resolve issues, only to have technician RE-INSTALL software, when I queried this with Advance repairs just got attitude and \technician has done his job"and if issues persists you must just book unit in AGAIN!!!<br> <br> Question how does re-installing software for a 3rd time \""solve\"" issues???? & spending 30sec on unit is not testing"