iPad Activation Lock

Hi. I bought an iPad from someone on eBay some time ago and when I got it from its owner, he forgot to remove the iCloud Activation Lock so now I can't use it. And I lost his contacts too so I can't call him to take it off either. It's stuck on the screen where it says the iPad is linked to an Apple ID.

So please help me. I can't pay for an iPad but don't get the opportunity to use it at all.

Many Thanks

Elizabeth