PayPal Failure?

-- HikaShop version -- : 2.4.0
-- Joomla version -- : 3.4.4
-- PHP version -- : 5.3.29

Heys guys,

I've been having issues with my website, some customers have called up our phone line explaining that once they get to the final step on our checkout which redirects to PayPal the page redirects to the PayPal front page instead of the usual payment screen. Any help on this would be greatly appreciated.

*EDIT*
I forgot to mention this is an intermittent issue which seems even stranger.

Hello,
I just tested it on my end and even on your website and it worked fine for me, without step by step instructions we won't be able to fully understand your issue and solve it.
Also, to be sure, can you download the last Hikashop version through our website, install it and test it again ?
Thanks.