I want to subscribe but can't via PayPal as the account is linked to ex's mobile number so I can't access. Any other way to set up payment for subscription please?

You can create a new Paypal account in minutes and pay your subscription fee for the new QB Online account. Keep in mind, the discounted rate is not applicable when you purchase the trial account.

https://quickbooks.grsm.io/UK

Hello Lisavplive-gmail, 

Welcome to the Community page, 

So you can request to get the number changed we'll need you to submit our short form linked below to update this - these forms are processed within 24 hrs and you'll receive an email to confirm once complete. The link is universal and can be used by our UK customers. So you can resubscibe two ways you can log into your account on a web browser and enter in your billing details and you'll be charged by us directly at intuit or you can download the app and pay a 3rd party instead so either apple iTunes or android google play for your subscription.