do you say all services were down or all service was down?
Either is correct - the meaning depends on the nature of 'service' versus 'services'.
'all' is used to refer to the whole quantity or extent of a particular group or thing:
He slept all day.
I carry all of the blame
After a hurricane, telephone, electricity, transport : all services are disrupted.
A train service can be disrupted by a strike, in which a partial service may still be possible, OR all service is cancelled.