if your phone number has changed, you can edit it in the Business Centre, under the 'Details' tab on the left. Click on 'Contact Details', and you'll be able to update your phone numbers and to choose a 'Preferred Contact Number', which will be displayed in bigger font and in a frame on your listing.
To find the Business Centre, use this link or hover your mouse over the profile picture on top right, and select Business Centre:
You will then be able to update your listing in your Business Centre.
Important: you need to claim your listing before you can access the Business Centre and edit your listing. This article explains how to do it.