Hi Rambo,
Thanks for adding the size 
I think the first place I would start with your exchange is post #2 here which includes more information about the two main approaches I would suggest when you are exchanging a mattress for another one and the store you are dealing with doesn’t have the best quality or value choices.
I would probably avoid this option since you could buy two mattresses for the same price as you would be paying for one. The Beautiful uses high quality materials but this is more than I would pay for a similar mattress when there are many good latex options available for significantly less.
This is also on the high side for the Pamper and if you did go in this direction then I would talk with some of the retailers in post #32 here to get a better sense of the prices that they may be available for elsewhere. I would also keep in mind that the PLB topper is about 15 ILD which is softer than the latex in the Tucker mattress you liked and in combination with the 2" of 21 ILD latex that is already in the Pamper (on top of a 6" 40 ILD core) may be too thick/soft for you. It may be more cost effective (if you can negotiate the price of the Pamper down more) to buy a 2" 19 ILD latex topper from one of the sources in the component post here which would be significantly less than the PLB topper and this would give you 4" of softer latex over a 6" core of 40 ILD latex would be closer to the specs of the mattress that you liked at Tucker.
This may be a good choice for a “base mattress” and you could also add a 2" - 3" 19 ILD latex topper (depending on how soft the mattress feels) from one of the sources in the component post which would give you some of the feel of a latex mattress at a much lower cost but you can see some of the Barcelona layers here (and a lower price for the set than you are paying for the mattress) and it still has relatively thick comfort layers and if they have other mattresses that use thinner comfort layers yet it would have a lower cost and may be more suitable yet as a base mattress for adding a 3" topper. Some version of this type of option would probably be the way I would be leaning if I was in your shoes but of course this doesn’t mean that someone else would feel the same way.
This would feel too much like “throwing away money” just for the sake of making it work to me.
In looking at their website they also appear to carry Ergovea latex mattresses but I don’t know the specifics or the prices of these but if they have a 6" latex version of this at a reasonable price then this may also be a good base mattress for adding a topper.
Phoenix