live chat for support leaves you wide open to all sorts of legal issues if you mess with a clients account.
i.e. you get a live chat from a client to say they have an issue and need your help, so you go into their account and change some settings or remove a file as instructed via live chat. An hr later you get a ticket from the client asking what has happened to their website as a file is missing and some settings have changed. so you explain about the live chat and find out the client never chatted with you ( it turns out to be a friend of the client), you have no recourse and the client can take action against you for messing with their account.
support should always be done via their client area as this way they have to login, so you are protected if anything goes wrong