That's your prerogative. However, the coupon code you used was not advertised anywhere that I am aware of, I assumed you guessed the code, you did not?
Everyone here knows I am a fair person, if I posted it somewhere I'll make it right, for 2.00 it's not a big deal to me, but in reality I am big on being honest in ALL my business dealings and that's for both sides of the transaction. If I go out of business someday for that, well that's on me. For the record, that code has only been used 3 times, and I gave the code to the people personally. Like I said, if it's posted somewhere let me know please, even if you don't plan on ever ordering.
It's a shame I'll lose a customer, but to my knowledge I did not promise a code and then take it away.
If you were misled by someone/something and it's posted somewhere let me know, we'll work it out.
EDIT: Just to be clear, as the above sounds confrontational.. it's not. It's just a statement of how I do things.
IF (and I am not saying you did) fish for a code and found one, that is in my view somewhat under handed and I don't take well to that.. If (and I am assuming you did now) find it somewhere I am not aware of, that is a different animal and I would honor it and then take it down wherever it is if possible.
As a vendor, you'd probably be surprised what I run into.