Leaking evap coil

I am a homeowner with very limited knowledge about hvac systems, so please bear with me--if you want to explain it like I was a 2-year old, that's fine with me!

My evaporator coil unit was leaking water, so the hvac repair person first blew out the drain pipe. It still leaked, so he checked the freon, said it was low, which, he thought was causing it to cool too much resulting in condensation everywhere in the evaporator coil unit. He filled it with freon, but it still leaked water. He checked the freon level again, said it was fine, and wanted to replace the evaporator coil unit. Given that it was old, and I have insurance for it, I told him to go ahead and order it. Now the insurance company called me to say that they had been informed by the repairman that they no longer make evaporator coils of that size, and there is not enough height to put in the new units. What they want to do is to replace my existing furnace with a new shorter one that would allow a new taller evap coil unit to be put in. OF course, the furnace is not covered, as there is nothing wrong with it, and I would have to pay for it. Is this a reasonable recommendation? The current unit is 28"l x 21"w, and is 18.5" high. The furnace is 46" tall, and the metal connection between the evap coil and the furnace is 6.25" high at the drain end, and 6.75" high at the opposite end. There is at most 3" of room above the evap unit before you get to the main ductwork.

Is there someplace I can check to see if I can find a coil that would fit? Is it worth having someone cut the side to determine if there is just a leak in the pan? If I have omitted any vital info, please ask. I thank you for any information you may provide.

First what I know about A/C systems says that your problem is the evap coil freezing up and then thawing--dripping the moisture as it thaws. Your repair guy did the right things --- clear the drain line and put more freon in.
Now it gets questionable... I'm assuming that your present unit worked OK for years without freezing up and then dripping(although they all do somewhat and that's why they have the drain).
Is it possible there is more infiltration of humid air now that condenses on the coil? Possibly the fan needs to run longer to keep it from freezing? Maybe the filter is clogged or the ductwork flow is restricted?
Unless you want to pay for the great cost of changing the evap coil(or maybe you just want a high SEER unit) you should explore other things first.