You will have choice to select payment via single payment or instalment when you're in the payment process.
After clicking on "Continue to payment" you will see this page
Select payment by eghl, and you will be redirected to this page upon clicking on "Complete payment"
Select instalment payment and choose the number of months you are comfortable with.
Do note that this only works for Bangkok Bank Credit cards.
Unfortunately, this instalment-free deal is only available only for customers who have Bangkok Bank Credit Cards.
Thank you for your kind understanding.