Try setting up the connection again from scratch (make sure your codes are in the right letter-case, my mate spent hours trying to work that one out!) If it still doesn't appear to be working, try moving your PS3 closer to your Network Hub (assuming you're on a wireless connection).
Checking with your folks. Thank you for signing up for updates from PlayStation. We have contacted your parent or guardian at the email address you provided. PS Plus: 14-Day Trial on PS4, PS3, PS Vita | Official PSN and PS Plus features and offerings may change without notice. HOW TO CANCEL Canceling your subscription from a PS4 System: Sign in to PlayStation Network, then go to [Settings] > [Account Management] > [Account Information] > [PlayStation Subscriptions]. After selecting the subscription you want to cancel, select [Turn Off Auto-Renew]. PlayStation Network | PlayStation
PS Plus: 14-Day Trial on PS4, PS3, PS Vita | Official
The official PlayStation™Store - Buy the latest PlayStation® games for your PS4™, PS3™, and PS Vita. PlayStation Network | Connect to our online world
To use PSN SM, you must have a Sony Entertainment Network account. To create an account, select (Sign Up) under (PlayStation™Network), and then follow the on-screen instructions. Main items required to create an account
Jun 12, 2020 1-Year PlayStation Plus Membership (PS+) - PS3/PS4/PS Vita PS4/PS3 Console: Log into your PSN (PlayStation Network) account. Click on the “PlayStation Store” icon. From the menu on the left, select “Redeem Code”. Enter the code you received in your confirmation email from cdkeys.com, and continue with the prompts. PSN license issue and how to get your PS4 games working Oct 27, 2016