Hey, @merinoyarn !
Thanks for sharing your concern here.
I can appreciate why this may seem out of the ordinary for you, especially considering the varying amounts and different types of cards being used.
May I ask if you have tried reaching out to this particular customer to gather context? To gather more information and confirm the intentions of the customer, you can reach out to them via a courteous and professional email or phone call. Keep a neutral tone during the conversation and ask them to confirm some things about their orders to see if things match up. There are also some other steps listed here, which might help you with preventing fraudulent orders.
While protecting your business from fraud is crucial, it’s equally important to maintain good customer relationships and ensure a positive shopping experience.
Aside from the above, how is everything else going with your business?