Hi, if she returns to the uk and asks the Turkish consul, odds are they will refuse a visa for 90 days (90 in 180)it's the official line. But, friends of mine have travelled back to turkey getting a new visa straight on top of the old one ! Snag is no one can tell u for certain how things will be so it's hard to advise, my friends will be returning in sept looking for their third 90day visa this year, this is bod rum of course. Good luck with it though.
Hiya, Mollag here, Extending her visa is unlikely to happen, its a mineield area with nobody really understanding it, 13 days left leaves little room to maneuver. Best i can suggest is that she does a fast run to Kos and try for another 90 days on return, i know many say this cant happen but i know of folk getting a back to back visa, its worth a punt. If they refuse it her present visa gets her back in to Turkey, then she would be best returning to the UK.
Good luck with it all!