Error When Purchasing - 400 (Bad Request)

Desperately in need of assistance here. I'm unable to purchase any new content in the Origin App or browser (incognito or otherwise). I have tried everything that I've seen in these threads including updating my primary payment info, using the Reset Origin tool, etc. I'm also not using a VPN. 

I'm just trying to buy the two latest kits for the Sims 4 (Grunge Revival & Book Nook). 

This is the error message I receive after adding the kits to my cart and clicking purchase:

An error occurred. Please try again later. [ref. #Error: httpRequest ERROR: https://gateway.ea.com/proxy/commerce/carts2/store-cart-purchase-client/offerEntries?storeId=Store-Origin¤cyCode=AUD&needFullCartInfo=true&needClearCart=true&countryCode=AU 400 (Bad Request)]