It stops working. I'm clicking away happily and then the button just stops working and no more items are received. If I refresh or move to another it works again, but stops shortly after.

You're probably clicking too fast. See here: Problems and Bugs: This is not a bug!

I am having trouble with vending too, if I can't get an item by clicking, I move to another machine. Last few times ive been vending, I noticed it is not telling me I vended 250 times already...here i am with 277 items in my inventory that I just vended.

That's fine. You have a GA, so you can vend double the amount now. :)

Gold Accounts: 2x Vending!