Not Being able to Purchase Sims DLC's on EA app

I have been trying to purchase a couple sims expansion packs (Get together and University) however, whenever I click "PAY NOW", the 'offline' window (The window you see when you're offline) briefly appears for less than a second then disappears and I am transported back to the home page of the EA app, and my cart still has the 2 packs and I receive no confirmation of my purchase, either from EA or my bank. 

The window appears and disappears too quickly for my to take a screenshot, however, I can provide a screen recording of what happens when I try and buy the packs.

I play on a Mac so I can't purchase any DLC's off steam either.

I have tried re-starting the app as well as re-installing it, but the problem still prevails.

Is there any way I can fix this issue or buy my DLC's from another platform? Thanks.

(PS - this isn't my first purchase, I have already bought many packs for the Sims already, this is the first time I'm facing this issue, and, it's not an issue with my card either as I've recently used it to purchase stuff online).