Hi lotus65,
The better options and possibilities I’m aware of in the Long Island area (with links to the NYC area as well) are in post #4 here. They include Talalay and Dunlop options that you can test (assuming they are in reasonable driving distance).
Latex in general is the most durable of all the foam materials and it has a long history of lasting decades in some cases (see the video here for one example).
I don’t know the specifics but I believe that the Classic Brands topper is blended Dunlop (partly synthetic and partly natural latex) which is usually less durable than 100% natural Dunlop when it’s made in a mold. It could also be connected to long periods of compression either in shipping or in a warehouse because Dunlop is more susceptible to this than Talalay. Finally it could also be that you received a defective product because even blended Dunlop should last much longer than yours appears to have lasted. How deep are the impressions when you put it on the floor (you can measure it with a straight edge or with a string stretched from side to side across the impression).
It’s important to check it on the floor or a firm flat surface because latex is very heavy and flexible so it could also be “following” or sinking into a soft spot in your mattress.
Phoenix