Why does Apple keep charging my cash app card

Pay with a different card instead of your default card

Here's how to switch cards:

• iPhone with Face ID: Double-click the side button. When your default card appears, tap it, then tap to choose another card. Glance at your iPhone to authenticate with Face ID, then hold the top of your device near the reader to pay. 
• iPhone with Touch ID: Hold your device near the reader without resting your finger on Touch ID. When your default card appears, tap it, then tap to choose another card. Rest your finger on Touch ID to pay.
• Apple Watch: Double-click the side button. When your default card appears, swipe left or right to choose another card. Hold your watch near the reader to pay.