Temperature gauge Keeps going up.

I have a 2010 Camry 4 cylinder. Temperature gauge
was fluctuating into the red then coming back
down. I had it checked it. They replaced the
radiator because of a small crack. They flushed the
system and replaced the thermostat. It was fine for
a two weeks. On a Saturday afternoon I noticed the
temperature gauge go up again then come back
down. I took the car back to the shop and they
replaced the cooling fans. One wasn’t working.
Now for a couple of days the car was fine. On the
fourth day the temperature gauge shot up maybe 5
minutes into driving to get my emissions test. It
went right up to the red line. Even past it a little. I
got my emissions test. The place is only 10 minutes
from my house. On the way home the gauge stayed
at the red mark. Went down slightly but still in the
red. What could be the issue here?