My client would like to turn incomplete orders into orders by automatically generating an email to send after a certain time period (eg 48 hours). I realise this cannot be done by default in Store, but is there any other way of doing this?
There is not an add-on that I know of that would be able to do this for you out of the box.
You would need to build an extension to handle this. There is currently not an extension hook in Store for abandoned carts so you would need to build an add-on. I have not updated a build to Store 2.5 but the release notes mention that incomplete orders no longer create an order in the orders table so you would probably need to query the
exp_store_carts table to see carts that have not been completed and have sat unchanged for X amount of time.
IT should be noted that you would only be able to do this if the user is already logged in to your site.