The situation is like this. For my site, any purchase above $30 will have free delivery (by our van delivery service), less than $30 they can pay for delivery or opt for in store pickup or by post. When a buyer buys more than $30, there is no selection for them to choose, it goes to delivery service. Some customer want to opt for delivery by post and pay for it even if its free delivery, how can I show the option for them to select this?