Pretty sure something like this has been posted before, but just incase it has not, here is a quick and dirty Dialog Spammer!
Very simple. It supports up to 3 Dialogs at the moment, but it is really easy and obvious how to add more. You pass them like this in the Dialog Input: "0x5D|0x99|" or "0x8B|0x85|0x99" without quotation marks. Times is obviously how many times you want to repeat the dialog. NPC is the name of the NPC to use the dialogs on. You can put quotation marks for this one, example "Boris [Merchant]" however it should work without. So far I have only tested with quotation marks.
It will GoToNPC too, but this causes it to jump around a bit so it looks a bit janky. It works fine however, and if you really wanted to you could remove the "GoToNPC" and just make sure you put yourself right in front of the NPC instead :)
Cheers!