For the following disputes you should contact the merchant first:
Recurring payments, direct debits, memberships and subscriptions
Duplicate billing or incorrect charge amounts
Refunds and non-receipt of goods or services
Incorrect payment details (paid by other means)
If you cannot contact the merchant you should fill out the transaction dispute form for personal credit accounts.
For fraudulent transactions you should immediately report your card as stolen and fill out the transaction dispute form for personal credit accounts.