Very cool.
Playing with letter substitution I managed to get this:
Osyowdsb aqtwdnk hdqq bdgo jtf k adayoos uowmosy ngxmtfsy ts jtfw soiy twnow
Entering florida will give you a fifteen percent discount on your next order
Code doesn't work though...
Congrats Hox for figuring out the code.
This is how I did it :
I had letters j & f decoded on my note, and I noticed there was twice the repetition "jtf" in the entire cyphered txt.
I thought this must probably be a common 3 letters word, like "the" or "you".
I tried with "you", making the letter "t" a decoded "o". So next was the encoded word "ts" who could only possible be .. "on", "of", "or".
Tried some more substitutions, more letters discovered allow to unfold other pieces of words. Then simply substitute, find a matching word, and repeat ...
Thank you for the pleasant surprise Polymerbit, I had a great fun time when cracking this !