In most cases, Apple handles all billing matters. Product Madness simply applies the credit once Apple processes the order.
Since we don’t handle your credit card, to request a refund, it’s best to contact Apple directly:
Visit the Apple Support Page page
Scroll to the bottom of the page and tap the Get Support -> Start now
From Billing & Subscriptions, tap Subscriptions & Purchases
Tap Request a refund and follow further instructions
Provide Apple with as much information as possible, such the Order ID for the purchase.
Sometimes, Apple can lump previous purchases onto a more recent receipt.