Call SNCF again-it seems they have 1 or 2 nasty staff who invent their own rules. For a week or 2 this was silent-maybe they were on holiday and have now come back. With lick you hit another one.

You did not say where you are now and how flexible you can be. There are still 2 TER trains via the local old line to Paris=takes much more time (comparable to in IT frecce vs regionale). If IN FR days before-just do it yourself on machine. Also try via Strasbourg and use local TER till there=more choice.

SNCF are quite picky about credit cards. Probably breaching EU legislation but that knowledge doesn't help. You can also call NS, who are not so picky. Or book via the B-Europe website, which has the disadvantage of a 4€ booking fee per order.