Paying with account balance is not available
Checkout refused pay-with-balance (premium.balancePayUnavailable; API may say “…on this site” / 403).
Why this happens
Admin disabled balance checkout for plans/traffic, or the feature is off for this site. Distinct from Insufficient balance (feature on, wallet too low).
Diagnose and fix
1. Admin: enable pay-with-balance / related Payment settings if members should use wallet funds.
2. Member: pay with Stripe/PayPal/etc., or top up first via Account balance top-up.
3. Confirm the product surface supports balance (some paths never do).
4. See Pay with balance.