Hi there and welcome
There is no number to call, but Gmail keeps an Activity log with IP Addresses of access to the account.
What he needs to do is go to www.gmail.com and sign into his account
In his inbox at the bottom you see the words Details which you can click on
You click on this and it will show all the recent access addresses to this account (the IP Address and location).
It does not show everything but this is all that's available, though if it was recent it will be there if she did hack it.
Then you would need to check what the ex-wife is using as an IP (you would need to go onto her computer and go to www.whatsmyip.com to check this, or you can see if the location is where she is.
But this is how you can see what activity has occurred on the account.
I would also advise he enables 2 step verification, so that any further access by the wife is not possible, and he can do this via the link below
If you \would like any additional information or assistance, please do not hesitate to let me know.
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