I have the same issue too with all my characters that have 20 days. Affected IGNs: Verent, Varzt, Verdent, Vlenn, LLnqxpresion, Raiichi, Vergent
To receive your coupon on the affected characters, please speak to NPC Vikin near the left side of Lith Harbor. Please let us know once you have been able to obtain the coupon. Sorry for the inconvenience.