6.35.11488 was released on 16th April.
The release dates are quite easy to find, look at the top of the forum and you’ll see ‘Announcements’ - click on it and it gives you the page where new versions are announced.
However it’s still not clear here if you have actually paid anything?
You don’t mention making any payment or giving any payment details.
So again - Have you actually been billed for anything? Or Charged for anything?
You only mention seeing a version update notice pop-up, and I think that I have worked out what you describe seeing.
Do you have both of these options ticked? (You should really only tick one or neither).
The top one if ticked updates your CCleaner version automatically for you.
The bottom one if ticked sends you notifications when an update is available.
(Most people want one ticked, the other ticked, or neither ticked.)
So to me it sounds as if you had both ticked, and so both happened.
You got a notification that there was an update available, and you also got the update automatically.
So when you tried to update again from the notification it of course said that you already had the new version.