In the Retell dashboard, open the Billing page and click Change payment methods — this opens the Stripe customer portal.
Remove the existing Link payment method.
Add your debit card by typing the card number into the form manually (decline any “Pay with Link” / autofill prompt so it saves as a card, not a Link entry).
Set the new card as the default, then reload the phone-number purchase page.
Let us know once that’s done and we’ll confirm the inventory call comes back clean.