I have already answered all these questions.
We have clear login details and passwords to exchanges but the 2fa is creating a problem. The phone he used is broken. My question would be can we reset the 2FA without the broken phone altogether via his Google account which we also have the sign in details for?
Since you have the 16 character 2FA back up codes, you should simply download an open source 2FA app such as Aegis and import the back up codes in to that app. It will then start generating the 6 digit 2FA codes you need to access his accounts. There is no way to recover a Google Authenticator database simply from a Google account unless he has exported a full back up of his 2FA app, which it doesn't sound like he has done.
We have seed codes for two exchanges and list of phrases (12 and 24 phrases). Do i have to contact the companies themselves to remove it or reset it or do i have enough details i can do this myself with the info that i have here in of infront now?
The 12 and 24 word phrases are to separate wallets and are nothing to do with his exchange accounts. Having the username and password, as well as the recovered 2FA code as I explained above, is enough to access his accounts.
At some point after you have sorted out accessing the exchange accounts you will want to import the 12 and 24 word seed phrases to a wallet to check for funds on them too. The easiest way to do this safely would be via a hardware wallet.