This payment method is not available for reseller checkout
Reseller top-up returned 403 when the chosen payment method is not allowed for reseller checkout.
Why this happens
Gateway enabled for normal checkout but not for reseller top-up, or client sent a disabled provider. Distinct from Reseller account is not enabled for your user.
Diagnose and fix
1. Member: pick another method shown on reseller top-up.
2. Admin: enable the intended gateway for reseller/top-up flows in Payment settings.
3. Confirm reseller account is enabled first.
4. See Account balance top-up and Select a valid top-up amount.