Originally I got that FP15 Discount code via email after signing up for their newsletter & Registering as a customer (I actually won a contest for a POD an nee to get some other "Stuff" so I signe-up) . . . When I finally decided to make a purchase, I had a problem with the FP15 Discount code too at first (I originally was registered as a Wholesale customer - Don't ask me how, but I was) . . . I contacted them via the Customer service "Chat" and I suddenly became "Retail" a week later . . .
Anyway don't know why the discount code didn't work for you. However, if it is not to late, I would try to contact them and have it "Fixed" for the extra 5% Off using "FP15" ( Like they say - a Penny saved is a Penny earned - which can add up to a dollar or even more to spend on more "Stuff"

) . . . Just a thought . . .
As a suggestion, since the price for the Minifit is so reasonable there - might I suggest Ya' try again. First sign-up for the newletter an register as a New "Retail" Coustomer. Then just wait for the email to arrive for the Discount code . . . Just a Thought . . .
YEP - That's how I got the discount code: CHEAPVAPINGDEAL . . . An got a little "Honey" credit too . . .
I Know - I Know - "My" Bad . . .
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