If what you have is from zamplebox they deal with a lot of different juice suppliers, mostly "little guys"
others may know better but I only saw a couple names there that I'd heard of before.
http://www.e-cigarette-forum.com/forum/general-e-liquid-discussion/487247-zamplebox.html
From the first page in the above link they are talking about it being a crapshoot when it comes to nic levels eg. take what you get sorta thing.
Most are probably small up and comers or crash and burners, probably made in kitchens or garages.
If you could contact zbox and tell them your problem?
Ask for half your next box to be high in pg,
and the other half to be high or 100% vg.
If that is possible.
And reaffirm it all must be zero nic.
Hopefully one type will be okay and the other will be good for the "old man"(PG or VG)
Chances are the liquids are fine but I doubt if some of them are made in "labs".
It is a fair price for a lot of variety, but you must realize at that price point it probably is very cheap liquid made with very low quality ingredients in very small batches and might also be older stock.
Big names like Hangsen, Dekang or other approved suppliers on this site might be of interest.
They will all have a track record and be in good standing if they are "approved" by ECF.
It's no "guarantee" but it's better than vaping all the unknowns out there nowadays.
Suppliers
This is just all only my opinion. TIFWIW.

Hope you get it straightened out. Cheers.