NexGuard review: Visa rebate $15.00 card

Got this in the mail from purchases of Nexguard Flea medicine at our local vet, but unable to activate it by phone or web site.
Card number is [protected] Exp. date is 01/22 code on back is code 327.
Keep getting message failed to activate. Telephone number [protected] also reports failed to activate. Unable to talk to live person on card or leave a message.
Attempted about 10 times on website and 10 times on phone.