Paypal express price not discounted

-- url of the page with the problem -- : www.infinityvape.co.uk
-- HikaShop version -- : 2.6.3
-- Joomla version -- : 3.6.2
-- PHP version -- : 5.6

The paypal express payment doesn't take into consideration the discount applied, so our client has to refund the difference everytime to the person buying their products.

Hi,

The PayPal Express Checkout plugin properly handle coupons on our end. And I'm not able to reproduce the problem on your website as you didn't provide a test coupon for us to see the issue. Could you do that ?
Also, simply turning off the "send order details" setting of the payment method should fix the problem since it would only send the total amount to PayPal.