Float has a great business model

Float has a great business model. I like it. It helps. However, in cases where large purchases are made, the outstanding amounts need to be reserved for the monthly instalment to then be deducted. My problem with this is that, I may have the monthly instalment in my account, but definitely NOT the outstanding amount that needs will be reserved - which then defeats the purpose of said business model (and then I’d have to pay off the FULL outstanding amount if the reservation is not done after 2 attempts - which then REALLY defeats the purpose).