Mohamed,
Thanks for the response but this is just a temporary fix as it is simply changing the pricing and is not time based. Also, if you forget the shipping price, it can cause issues so I just decided to disable the shipping method late last night and will re-enable it late tonight. Honestly, a shipping discount setting in the discount record would resolve a lot of issues as quite a few shops offer free shipping during special sale periods.
Also, auto-loading a coupon is great BUT you still can have it to offset or remove the shipping costs so that wouldn't work.