Call Horizon Customer Service at 1-800-251-6144 and tell the representative you want to cancel your card. If you call within 30 days of your billing date, you may be entitled to a partial refund of your membership fee for that month. You will still be liable for any purchases you have made using the card, plus applicable shipping fees.
The Horizon representative may try to persuade you to keep your card and membership. If your objections is over the monthly fee, you may be offered a reduced rate of $6.95 per month. That has fewer benefits, but still allows you to purchase items with your card on the Horizon website. If you do not want to take advantage of this offer, you may still cancel your card. Write down the name of the person you speak with. Before you hang up, ask for a confirmation number to verify the card has been cancelled.