$50 Bounty for what I'm sure will be a simple "execute some php code" conditional action.
My store contains products of 8 different classes. To checkout, the customer MUST have selected 1 (and only 1 ) of either of 2 classes.
If the cart does not contain 1 (and only 1) product of either of these 2 classes, an error message should be presented to the user in the checkout, and they should be prevented from completing the checkout.
The earlier in the checkout process the better.
I have tried creating a triggered action on Calculate sipping costs that Displays a message to the user. This successfully prevented checkout but did not show the message.
Bounty to be paid on a successful tutorial and/or php code.
Cheers,
Danny.