PetFlow Customer Service Ignores My Subscription Cancellation Issue

My cat has moved to a different brand of pet supplies, therefore I terminated her subscription to PetFlow last month. I was able to easily cancel my membership by contacting customer service. Six days ago, though, I saw that they had left my monthly order as usual. After canceling the transaction, I contacted customer support to find out why they had sent the goods and charged my card again. Instead of listening to my concerns, customer service agent Helen persisted in promoting the brand. I would like a refund and for your company to delete my credit card details from your records because my cat is no longer interested in using your products. Please provide me with a physical document attesting to the cancellation of my membership if at all feasible.