You can have payment options as Polipay and Bank Transfer using Osko and the quick deposit system. These are great options to reduce your fees and charges per transaction but the risk applies before the money is cleared to your account.
Orders are transferred to Retail Express when they have a paid and processing status. If they are not in this status Retail Express does not know about them and the products will not be allocated to this order.
For example :-
Polipay is currently set to automatically turn orders to processing, while with Bank Transfer payments I manually turn orders to processing when I see the payment in our bank statement.