If you have these ingredients (minus the chilis), mix these ingredients together (you do not have to use all, but it works better) it would definitely tone down the heat without compromising the authentic Thai flavors.

But if not worth the purchasing the big 5, the usually way to "wash" off the spicy oils off the palate is to wash it away with another. Coconut milk is a good alternative, or if you could mix a little milk and peanut butter, to make a little sauce. These still have Thai flavors. Just be sure to mix all ingredients well.

However, if these ingredients are unattainable, you could always drizzle a little olive oil or creme, dollop of plain yogurt or sour cream, or squeeze some lemon.

Or then there's just braving the dish out, and treating your courageous self with a bowl of ice cream (preferably coconut) right after!