Skrill not returning payment complete

[0121stephen]

Hi,

 

I am using the Skrill module v1.0.38 with Prestashop 1.6.1.18.  I am using a multistore site.  Customers are able to place an order on the site and payment is accepted.  However, the order status is not being updated and the cart is left with items in.   This issue seems to affect some multistore sites but not others.   I am having to go through Skrill and manually complete orders on my site.  I have contacted Skrill who have advised they are receiving 500 Internal Server Error when they send a message to my site to automatically update orders.

Any ideas how I can fix this?

 

Many thanks,

Stephen