client bait and switch

what do you do when client calls you and asks you to do x only, and you give him a quote of $100. he never mentions anything about y or z. then he sends you a confirmation email
please start. as agreed over the phone, I will pay $100 for x and y and z.

1) this guy is too much trouble. block him
2) clarify that you are not doing y and z

I am not asking what's the "right" thing to do because obviously what's right for you may not be right for me. but what do you personally do in these situations?

1, or charge him $300 upfront for the work together

Just tell them you never agreed to do y and z for $100, so you'll either do just x or charge more and do y and z.

It is simpler to refuse because that dude tells nonsense

I would politely point out that you only agreed to do x for 100$, but would be happy to do y & z at 2x-20x your regular price, depending on how important/stupid the client is. Either you get revenge and profit, or get rid of a time waster.