What to do when order is wrong?

I put in an order on Christmas day on Bricklink. 16 unique lots. Total was like $11 including shipping. They sent me a tracking number the same day.

I got it today and two lots are missing.

Honestly - I am super grateful that there are folks selling teeny little lots like this to me so I'm inclined to just re-order from another seller but I'm curious what you all think is the right thing to do.