Sealy Sotheby uneven?

We've recently bought a Sealy Sotheby latex mattress which we thought was fantastic in the show room at first. We have noticed that the topper that's stitched onto it is showing signs of uneven wear between me and my husband. We've also accidentally spilt tea on it. I know we can't return the bed because of this but after 6 months should the topper be so uneven and lumpy?

My husbands side is almost flat compared to mine!!

What can you recommend to help resolve the dip situation and what would you recommend to get the stain out so we don't damage the latex?!

Lisa