The following was adapted from a post in the Adwords Help section:
You can locate the chat icon by visiting the main help section https://adwords.google.com/support/aw/ and scrolling to the bottom of the page. Click on the link “Contacting Us”. Then, you’ll find more links. Click as deeply as you can, i.e. the link for “Billing and Cost Control” > “Settings, Budgets, and Bids” > “Daily Budget” (until there are no more pop-down links as options become more detailed). Only then will you see in the bottom right corner, “Have additional questions?” and it will give you these options:
– Visit the AdWords Discussion Group
– Email AdWords Support
– Chat with an AdWords Specialist
Note that this doesn’t work ALL the time – sometimes a chat support specialist isn’t available at the current time. Just try later on in the day.