The only experience I've had with this is via Student Flights. I paid for economy tickets via Lombard Finance - I HIGHLY RECOMMEND NEVER USING THIS COMPANY. They were able to view a lot of personal details that they shouldn't... aka your account password.
However, with them I was able to pay it off over 12 months. I'd check with the hotline to ensure the correct details because sometimes they give you a certain amount of time to pay it off before they start piling on a tonne of fees.