In the last year this plugin has gone from being pretty good with the occasional hiccup to absolutely diabolical.
Support is non-existent, with no reply to numerous reports of problem.
- coupons are broken, and don't handle % discounts correctly when VAT is into account. Detailed report provided but no response. So can't use coupons internationally.
- orders often don't include VAT when the order is outside of the UK, despite the rules being set up right (and having worked fine for years). For example, just received an order from a customer in Holland: no VAT added for absolutely no reason. It worked before.
- more subtle errors, not show stoppers, dutifully reported but ignored.
- WorldPay support no longer works for their current offering (installation key based, no longer API key)
I highly recommend you steer well clear of this plugin and chose something else. I'm going to migrate to another eCommerce offering now as it's beyond a joke.