You don't need to contact eBay for this, as they will tell you to follow the instructions I can give you now, as to how to proceed.
One day after the item's last estimated date for delivery open a case for item not received. If these were 3 separate orders, then open 3 cases.
Go right of the item purchased, and from More Actions select.... I Have Not Received My Item.
If you are not fully refunded within 3 days, you must escalate the case on day 4 or within 30 days from opening the case, and eBay will step in and force the refund.
Do not close the case early for any excuse or promise the seller may give, and do not forget to escalate.
@charz232012