Apply discount at the end of checkout.

I’m having a problem with the plugin. I’ve set an option that after a certain amount, shipping is free for my clients. I also wanted to activate your plugin to give my clients the option to pay by bank transfer and get an extra discount of 10%. The problem is that the discount is being applied before the calculation of the free shipping, so that is making my clients buy more to get the free shipping.
I would like to know how can we apply the discount of 10% by bank transfer at the end of the checkout, after the free shipping is calculated.
Thanks!

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