Change Operating Days

Hi.
Due to the some restrictions I am currently not able to be in my office on Fridays, There for am not able to Make and send orders on Fridays. I have a Personalised Gift shop, So buyers Thinking I am able to make and send for an extra day puts a lot of pressure on a Monday. I am able to make and send all orders on the Monday but the Delivery times are just a Day out

Does anyone know how I can change my Operating Days. They are currently set to:
Monday, Tuesday, Wednesday, Thursday, Friday

I would just like to loose the Friday. I have spoken to Seller Central but am getting nowhere. This seem pretty basic information that as the Business owner I should be in control of?? eBay & Etsy was a very easy unclick > Problem solved.

I know I could Deactivate my listings Thursday night, But like I said I can handle the volume on the Monday, I just need the extra day adding on the expected delivery date when customers place the order on the Thursday night/Friday. Just as it does because the system knows I am not operating on the weekend

Any sight, very much appreciated
Thank you
Jessica