Huh, I suppose "tanning" is the same as "steeping?" If it's the same no matter what carto, then I'm leaning toward it being an "off-batch" and unfortunately, I doubt time will help it... but you never know.
They may also be waiting to see if there's any other complaints on that particular batch before they do anything, just to make sure it's not a "personal taste" thing. But I'm just guessing on that one.
Oh, and here's an example about reviews (although this is dekang, not Top Vapor):
USA Mix, 50ml, 24mg E-Liquid
The latest ones have bad reviews, whereas the previous ones are more positive. Whether it's due to a "bad batch" or just personal preference, I can't say for sure.
Also, as a comparison, that one is 10.99 for 50mL. I was in a bind and had to get some stuff locally - I got 20mL of the exact same stuff for 19.99 at a smoke shop... Yeah, it sucks being a procrastinator, lol... I'm not a fan of dekang, but if you're going to try some, I don't think anyone beats MV's prices.
I've got a 50mL of DK-TAB on order just because of the price - I may not be a fan of dekang, but I'm a fan of saving money!