Switching Client's Old Site to Squarespace

I am new to building and transferring websites for clients.  My client has a domain that they would like to keep, but he currently uses a different web design company.  They are being difficult about transferring the domain to google domains so that he can actually retain all login and 'own' his domain.  This is the email he received from his current provider:

"Sorry, but he will have to set up a new hosting account somewhere else for the new site

as XXXXXXXXXXX only allows my sites and his own on his server. So there is nothing you need

from me."

One thing to keep in mind when transferring a domain is are there other services attached to the domain? Email being one of the most important. If your client has a custom email address for example < client.name@client-domain.com >. Then someone is providing email hosting services and you'll want to make sure those emails keep flowing. Of course along with all the other services that could be attached to the domain.

When the other designer says you need nothing from me perhaps they are telling the truth. They could simply mean that if you request the domain to be transferred to Google they would not block the request.

If you can tell us the domain we may be able to suggest other strategies. There are tools that can be used to examine domain names. How much can be discerned depends on how it was set up.

Let us know how it goes.