How to configure Shipment Rates, when Coupon's are used for payment

[schmaly]

Here is the issue. I offer free shipping for all purchases above amount X. No I sold 5 Vouchers with amount Y. When using the voucher, the amount X drops to 0,01 (so its below X), and automatically adds the shipping rate - but the purchase is way above the amount X (just payment is done with voucher).

Any ideas?

(by the way.. i also don't understand way the amount will not drop to 0,00 (when voucheramount is high enough - but 0,01)...

here is the site: goo.gl/mwbz0h