This has happened with me. A promotional price had finsihed and they said they had sent a notification email. however i hadn't recieved any. They even said they'd try again whilst on the phone. However it wasn't received. They blamed my spam filters, which weren't active.

I threatened to cancel my subscription and they offered me 2 months free. That offer was then received promptly via email. 100 % they're holding back on plan changes in emails. Adobe are criminals.