2012 Jeeb Liberty heat problems

I have a 2012 Jeep Liberty. Back in 2014 I
had to have the heater core replaced as I
had no heat. Here we are Oct of 2016 not
once but twice my care was in for heat
problems. I bought a warranty when
purchased the car so it should only cost
me 100 deductible. They replaced the
thermostat and flushed out the heater core
was charged over 500.00 and still did not
fix the heat. Brought the car back into Jeep
to fix my heat AGAIN!!! I get a call telling
me "Oh Yeah that heat is working fine. To
my amazement I was baffled it only works
when it's at the dealership? Had an other
person pick up my Jeep that now has
heat!!!! Mind you it's winter and here in
New England it's cold. Was so happy I can
get in my nice warm car to drive to work
without 100 layers of clothing on me!
Guess What!! No heat!!!!!! Ok Jeep I'm
giving you one more chance to fix this
problem or I want a replacement car. I
thought if a vehicle when into the shop
more than three times they have to replace
the car?