Box spring for latex mattress

We have been sleeping on our new bed for about two weeks. A few notes:

-When we originally called Latex Mattress Factory to talk about ordering the bed, we talked to someone who told us it would be way more expensive to have the latex for our king-size bed cut into two pieces. This was frustrating because we wanted them in two pieces to keep our options open, but we ordered the single large pieces for cost reasons. We recently spoke to another person at the company who told us that was wrong, we could have gotten the latex cut in half for the same price. This would have benefited us because we had a terrible time putting the bed together and it would have been so much easier with smaller pieces.
-While putting the bed together, we damaged some of the latex. The large sheets are so easy to rip, and pieces of them sheared off as we carried it around corners. The firm layer on the bottom has a big tear in it. We also spilled a potted plant all over the latex, and were able to vacuum up the dirt but we couldn’t get the stain out.

After sleeping on it for a few nights, we were surprised by how firm the bed feels. It did not feel that firm in the store when we were lying directly on the latex layers. We saw from a few posts here (https://forum.mattressunderground.com/t/new-latex-mattress-too-firm) that there could be a “drum” effect from the mattress cover, protector, and sheets, so there’s a chance those could still stretch out more. We then added a soft 1-in bamboo-fill topper: Amazon.com

Now, with the topper (and before we added it), when you press down on the top of the mattress with your hands, it is extremely soft and “sinks in” a lot. We’ve also found it’s very comfortable for belly and back sleeping. The problem is that I’m a side-sleeper, and while my shoulders are comfortable, I’m not getting any pressure relief in my hips. My hips are not “sinking down” enough. I think there’s a chance it could still be the “drum” effect, but we only have two weeks left in the return window for Latex Mattress Factory.

So we called them up today and Thomas at Latex Mattress Factory extended our return window. He thought the best solution would be to replace our bottom layer with Medium (instead of Firm). So then the mattress would be three 3" layers of Soft-Medium-Medium.

Their policy is to only allow one exchange per year because they shred the latex after it’s returned, so we’re concerned about excluding other possibilities that we should try instead. We asked Thomas about ordering another Soft layer instead, so that it would be Soft-Soft-Firm, but he said that was more likely to cause back problems.

Phoenix, in your understanding, is this good advice? Do you think another Medium layer (Soft-Medium-Medium) would solve our problem?