Shipping policy

My shop is a preorder shop. It is clearly stated under each product. I keep nothing in stock (as clearly stated) and order each item individually from Europe. The customer asked me on Friday what was happening with her order and I responded timely letting her know that my shipment had just arrived that day and I would be shipping it out over the weekend. The customer then requested a charge back even though I responded saying it was shipping. I shipped the item on Saturday. This is completely unfair use of this option. I’m a small business and I don’t appreciate this one bit.