Liam
I would have to recommend Click4Assistance they are the leading live chat provider in the UK, my company have been using their services for years and I have nothing but good things to say about them, they host the software themselves and know our data is completely safe. We have been able to customise the buttons and windows exactly how we need them to be, the support has been fantastic as we have had one point of contact who we can always speak to. You can check them out at click4assistance.co.uk
I am voting for Click4Assistance!