I can see the urgency of getting this resolved, @KRD62. With this, let me route you to the best support who can provide the appropriate details you deserve about keeping your client's QuickBooks Payroll Core account and its setup.

When your client is subscribed to QuickBooks Online (QBO) bundled with payroll, canceling only the QuickBooks (Plus) plan and keeping the Payroll Core services isn't an option. 

Since the Community is a public forum, and we'll need to collect some personal information to pull up your account, I encourage you to reach out to our Payroll Care team. They can securely pull up your client's account and provide options as to how you can keep their payroll account and setup. To do this, here's how:

1. Sign in to your QBO company.
2. Go to the Help (?) menu.
3. Select the Search tab.
4. Click the Contact Us button.
5. Enter a brief description of your concern in the What can we help you with? field.
6. Select Continue.
7. Choose a way to connect with us. Make sure to initiate contact during support hours. 

Also, to further guide you in wrapping up this year’s client's payroll and preparing for the next with QBO Payroll, I'd recommend using this year-end checklist: Year-end checklist for QuickBooks Online Payroll.

Please let me know if you have other concerns about managing your client's payroll account and transactions in QBO Payroll. You can drop a comment below, and I'll gladly help. Take care, and I wish you continued success, @KRD62.