'passilflora' dying what could be the problem?

Trouble with against walls, is it shelters soil along the wall, so it may look wet but not actually soaked in. Give it a really good soak over next few days even if it does rain! and perhaps trim it back a bit to give it less foliage to try an support with water.
How far is it planted away from the wall, needs to be 18-24 inch, away from rain shadow of wall. Waters the key! i think!

Yep, agree with Nicky above - no plant should be any nearer than a foot to the base of a wall or fence, because its a very dry place to be.

Dear Nickyt08 and Bamboo-have tried as you suggested - think you were right but probably too lat now, as what little foilage left is brown and v.dry. All what was new growth (ie now stemlike) also appears dead and almost woody. Any point in cutting off this metre - would take plant back to size when bought or should I give up and buy new next year? Thanks so much for advice.Janmh

I'd cut off any obviously dead growth (which might mean back to the base) but leave anything that might conceivably still be alive. Leave it in situ till next Spring and it might grow again then. Keep it watered if necessary.