Q: iMessage & Facetime not working

Hello, for the past 3 days I've been unable to use iMessage & Facetime on my iPad3. v7.1.2

Internet works fine, I can log into my Apple account, even use iCloud to sync my contacts etc. When I try to send an iMessage I'm asked to sign in (never been asked since first registered the iPad) so I enter Apple ID and Password and after a few seconds of trying to connect I get the message "iMessage Sctivation Could not sign in. Please check your network connection and try again."

So I did even though all other devices on the network work fine, no change, tried a neighbour's network, no change.

Exactly the same thing happens with Facetime.

I've restarted, even changed my Apple password. Can think of nothing else to do, any ideas gratefully received.

Many thanks.

David