Why didn't my VAMPIR coupon reward arrive?

The most common cause is checking on the wrong character: if your account has several, the reward only shows on the character you redeemed with. Open the mail on that character; if it's still empty, log out and back in.

VAMPIR coupon reward summary card: the reward goes to the logged-in character's mail, the launch-night bug was fixed on October 27 and rewards mailed on October 29, on iPhone use coupon.netmarble.com with your PID
Coupon reward: where it goes
Source / rights
Image / usage information: © VAMPIR Global. Official server website, used for sourced game reporting. · Image source ↗
Short answer

Coupon rewards go to the mail of the character you're logged in on; log in again if you don't see it. The launch-night bug was fixed on October 27 (UTC-7) and missed rewards were mailed on October 29. On iPhone, redeem on Netmarble's coupon site with your PID.

Was the launch-night coupon bug fixed?

Yes. According to Netmarble's known issues notice, rewards not arriving after a coupon was used was fixed on October 27 at 20:05 (UTC-7). Affected players got their rewards by mail on October 29 at 04:15 (UTC-7). A similar Twitch Drops bug was fixed on October 27 at 19:39 (UTC-7), and missed drops arrive by mail.

How do I redeem a coupon on iPhone?

There's no in-game coupon box on iPhone. Redeem on Netmarble's coupon page with your member ID (PID). The PID is in game under Menu > Options > Account/Terms of Service, on the Account Information (PID) line.

VAMPIR Options menu with the Account/Terms of Service tab, the Account Security button highlighted and the Account Information (PID) line below
PID: Options > Account/Terms of Service · Image: Netmarble
Source / rights
Image / usage information: © Netmarble Corp. & Netmarble Neo Inc. Image from an official VAMPIR global notice, used for sourced game reporting. · Image source ↗

FAQ

It says the coupon code is invalid?
Type the code again, minding upper and lower case, and check it hasn't expired. Current codes are in the coupon code guide.

Related guides

VAMPIR errors and fixes

How to redeem VAMPIR coupon codes