Hello, Alex
This is William, you skype friend
I would like to speak to the manager/to you
我想跟经理/你 谈谈。
Speak to means " 对 xxx 讲话/谈话/说话“。
Also how do you say the more informal word "chat"
Chat informal expression is 聊天,闲谈,闲聊。
Please note even they are informal expressions, they are not dialects.
So everybody in China can understand it.