Canadian merchant and Canadian Amex account?
Yes, a Canadian merchant and my card is Canadian. Originally was told they could stop future charges by changing the credit card number. When more charges went through the next AMEX employee said the first one was wrong.
It may be a pain to call in to pay each month, but if you set up auto-pay, your ability to threaten 'fix it or no money' is gone. Merchant knew this and told me too bad, you pay anyway.
Resolved the issue myself, no thank you American Express.
Until this experience, I really thought I was the customer. Now realize the merchant is the customer. I used to swear by AMEX customer service, no more.