Debit Card - Car Hire

We use Tempest on a regular basis and unfortunately our staff do not have credit cards, so the booking is made using a debit card.. As such we transfer money to the relevant person and they then pay using their debit card. Lately, we have had instances whereby, due to work commitments at site, in Rustenburg, our one Contractor is required to stay longer then the car booking dates. This then requires him to drive from Rustenburg to Lanseria to pay for the additional days. You already have a deposit amount, so why can't this balance be EFT'd (immediate, if need be)? It wastes an entire day for him.