I'm using a template delivered with One Step Checkout.
I set up 2 different shipping options: - free shipping - express shipping
By default Free shipping is always selected. I have no problem with that.
But when a customer clicks to select the payment method (paypal), then the cart reloads and the shipping becomes free shipping, even if express shipping was selected before.
How can I prevent such behavior?
You can have a look at www.tendance24.fr if you want to test the bug.
To reproduce on the order page select a paying shipping method, it reloads the cart calculation (Ajax update), then select the payment method, let it load, you'll see in the price description that the free shipping has overtaken the paying one we selected earlier.