C'est la croix et la bannière

Literally: It is the cross and the banner

Example: “Pour obtenir un rendez-vous chez ce médecin, c'est la croix et la bannière.” — Getting an appointment with that doctor is a real ordeal.

English equivalent: Like pulling teeth

Origin: A form of this is attested from the 15th century, borrowed from Italian, with the phrasing used today on record from 1822. Religious processions once carried a cross at the head of the line, along with whichever banner suited the occasion — a parish's, a confraternity's, that of an important visitor being formally received — and organizing that procession correctly meant following a thicket of fixed rules about who walked where and carrying what. Furetière's 1690 dictionary already has il faut la croix et la bannière pour inviter quelqu'un — you need the cross and the banner just to invite him — meaning the invitation had to be so formal and so hard to refuse that the person couldn't decently slip away, which is the seed of the modern sense: a process so laden with procedure that finishing it feels like an ordeal.