Hi @SciEnce P,
You can refresh the page and it may appear... and/or give it 12-24 hours for it to show up in your billing section. Also, if your payment method flags the payment after it was done, it can slow the payment processing and it could take longer or actually show back up as a declined payment. Most everything gets settled in 24 hours but unusual situations could push that timeline to 2-3 days (which is not typical).
Further, if you wish, you can open AdWords and click on the gear icon in the upper right hand corner and call the phone number shown and seek help from support directly. They can access your account with you and tell you precisely what is what.
Google AdWords Top Contributor | Google Partner | GYBO | Local Guide | My Profile