Are you sure you are measuring the gravity correctly? The beer would likely be noticeably sweet and likely cloying. Of course if you brew with high amounts of crystal malts, you will have high final gravity.
Fermentation temp and pitching rates are vital to producing quality beer. Yeast need the right conditions for to live and thrive in. If the temps are too high they will burn out too soon. If there are not enough yeast for gravity, they will poop out before fully attenuating the wort.
For your climate, you need to be creative in keeping the wort at the right fermentation temp. bathtubs, tubs of water with ice, fans, wet towels, temp controlled fermentation fridge. Something! Getting the right amount of healthy yeast is easier. Things like hydrating dry yeast, starters, adequate oxygen, nutritional aids.
As for the terminator, I found that with ll plate chillers, you need to be pushing a good volume of water though the chiller. All plates should be touchable without pain to the fingertips. Crank up the water pressure. I prechill the water going into the therminator to achieve a 50 or 55F in temp.