The fact that your cheese was labeled as double cream cheese is interesting - it makes me picture a cheese that's very soft and fatty, like a double cream brie or similar, or else actual cream cheese (in the a-bagel-and sense). I don't think these kinds of cheeses slice particularly well, so it may not be the same as what you tried or I may be off in my interpretation - but imagining either of them in the flavor pairing makes me go interesting and wanna-try-it.
And you might consider manually adjusting (ie, a dollop of cream cheese plus some curd cheese, or else plus some stronger saltier cheese to balance it out, sounds like a really good approximation for a very rich cheese melty about the edges)
Also, despite your reservations you probably can use Queso Blanco if you find it (irrespective of it possibly not being labeled "Columbian"). Or you can try the Queso Compasigna you mentioned finding. Other names to keep an eye out for are Oaxaca cheese or Chihuahua cheese - they are all generally mild melty white cheese, but specific branding may vary by location, marketing, and other factors.
Queso Blanco is a generic name, for a generic cheese - and it is true that it can come in a variety of styles and methods. However, I usually find it is functionally a melting cheese - that style suits the young, mild flavor and generic name, and it is generally acceptable for the uses it is intended for. I have seen something with that name that was a frying cheese, but even then it was labeled as such - and even frying cheese softens and melts a little with heat, so it might not do terribly in your hot chocolate.
If you none of those appeal, then some mild young melting cheese will probably do. A couple other answers have mentioned muenster, which is nice, or fresh mozzerella - which is stored in liquid, and melts in puddles, and is generally fundamentally different from the dried, aged stuff that can be sliced or shredded.
I also thought of using farmer's cheese, or hoop cheese - both names for a generic mild young cheese, which can have varying states of firmness vs meltiness (paneer vs cheese curds vs something with the texture (not the taste) of milf melty cheddar), but usually more developed brands get a unique name - this stuff is just young and mild. And really, any of it should be worth trying out, the flavor profile is pretty similar.
Depending on preference and availability, you might also consider other options like butterkase cheese, or jack cheese (like Monterey jack, but check young vs aged), maybe provolone if you want something a touch stronger in flavor, Havarti - especially unflavored ones, there are a lot of herbed or spiced versions, or even possibly a young gouda. None of these will be quite like your "queso doble crema", but they may be tasty in their own right, and worth trying either for local availability or for personal preference.