Can't Establish a Reliable Connection to the Server

I've read a couple of forum's relating to the same incident, but no solution has really worked for me. So, I have an LG G3 D855. Which I preordered. I had decided to root the phone, and was working fine. by the 29th of November 2014, my play store had stopped working. I had contacted google and they said they can't do anything about it since I had rooted the phone. I then decided to unroot the phone, which didn't work, and perform a complete factory reset. And still nothing. I've only brought this problem up now because the digitiser broke and I have only recently performed a D.I.Y fix on the screen. It currently has the latest update, and I still cannot use the play store. Another forum said to root the phone and use the app 'root explorer' to remove a couple of files. however I recently attempted to root via purpledrake and came up with error, which told me I am unable to root the phone with the latest update. I also do not own a windows computer, only mac… which makes things a little more difficult.
If anyone could please help me it would greatly appreciated.