Pulling data from ticket fields to user record

Hi Brains Trust

Hoping for some help on a particular use case. We have our Web Form in the Help Centre that is open access (e.g. users don't need to log-in to access). We request the user to fill in their Name and Mobile which are custom ticket fields (along with email which is a standard Zendesk field for webforms). 

Where the user is new to Zendesk, a user record will be created, but it will create with the Users Name as the left hand side of their email address (before the domain). This looks unprofessional in the acknowledgement email, as we've specifically collected their name in the form but not used it. It will also create work for the agent to remember to update their user record to copy the name and mobile (if provided).

I was looking to using a Webhook, but I don't think I can use this to update the standard Zendesk fields on the user record (e.g. Name & Phone). 

Anyone facing this same issue and has any solutions?

Thanks in advance!