did they trace it with a leak detector and it was coming out the condensation drip tube
^^^This^^^
You will see the dye coming from the drip tube. Any funky odors from the HVAC vents?
The condenser is also susceptible to leaks from road debris, also check the fittings on the rear of the compressor and the clutch.
I'm not trying to sound negative, and point fingers, but just giving you some food for thought just so you have crossed all your T's.
Wording this carefully as there are many honest shops around....but I've seen and heard of many tricks to get a big job and having been through that I try to stay on top of things.
If a shop told me my evaporator was leaking, I would get a can of dye and run a bunch through the system. I would let it run for about 30 min and check all over the condenser coil, compressor fittings, high and low test ports, and if it came down to testing the evaporator, if you have the removable access panel behind the glovebox for a cabin filter, I would take a peek inside.
But what
@Mooseman touched on, is I would absolutely need to see some dye on the ground or coming from the drip tube.
Just looking out, please keep us posted.