Backagain. After testing your plugin, there are a couple of issues and I thought you might be able to tell me where to look to correct them. I am using the demo account at First Data.
1. When I turn on "Allow payment notifications from %s" the checkout fails and I get a form submission error email from First Data with the error "x_relay_url : Invalid x_relay_url. Must be the same as configured for the payment page". Ifm I turn it off, the error goes away and the transaction completes, EXCEPT:
2. When the transaction completes, and I get to the Thank You page and click the link to return, the order shows created but it is not confirmed. It appears that nothing is coming back that tells Hikashop to confirm the order. I get all of the completion emails that show the card was authorized and payment made. I see in your plug in at line 289 that you are setting a confirmation function if the api is AIM, but I don't find anything that would set the confirmation if we are using SIM. In the default plugin there are some functions to deal with aim, sim and dpm. Since we are using the SIM api, it looks like your plugin is not returning a payment confirmation for that API. Any ideas where I can add it? I am not a real good coder, especially hacking someone elses work.