Don't bother messaging your seller again, just go to the Resolution Centre and open a Not as Desctibed dispute citing 'Faulty or parts missing'
Seller gets 3 days to send you a prepaid return label foryou to return the whole lot for a full refund.
Seller may say he will post you the missing parts, if he does be aware of the timelines - you get 30 days from delivery of the item to use the money back guarantee, so make sure he doesn't run you out of time.
It's always better to get your money back and buy again.
