Please contact H&R Block as soon as possible at 1-866-353-1266 to minimize your losses. If you contact H&R Block within 2 business days you can lose no more than $50.00 if someone used your card without your permission. If you contact us about a dispute and request an affidavit, one will be provided to you. Or, you can submit your dispute in writing to Cardholder Customer Service, PO Box 10170, Kansas City, MO 64171.