Q: Activation locked iPhone

You've

just wasted hundreds and hundreds of pounds on an iPhone you cant use

Sorry to tell you this.

Read more about the Activation Lock.

Find My iPhone Activation Lock: Removing a device from a previous owner’s account - Apple Support

Seller statement about no refunds does not over-rule eBay policy.

If the iPhone was not described as Activation Locked, open a claim

with eBay.

No, Apple cannot help you.

No.

Take a look at what imobl has just written. This makes sense.

No, Apple will not help. This is a 3rd party transaction between

you and the seller. Use eBay's buyer protection and open a claim

immediately.

Be careful of the time limits to opening a refund claim with eBay. If the

seller delays you past the limits, you will have no recourse. eBay is not

lenient on extensions from what I have read about such situations.