May 3 and 4 are scheduled strike days. We will be in Chamonix May 2 with a purchased ticket to Annecy that day. May 2 is not a strike day. I would like to modify that ticket to travel instead to Paris on May 2. We fly home on May 5 so I need to get to Paris while trains are running. Do I have to buy another ticket to Paris and just eat the ticket to Annecy? What should the SNCF do for me?
If the ticket is non-refundable and the trains are running you likely have no recourse. You can ask of course.
I looked at changing our reservations for April 28 (a scheduled strike day) to April 27 -- it appears that I could cancel, get a full refund, and re-book for the prior day AT CURRENT FARES (about €100 more.) And nothing said about refunds on May trains yet, just April. We will hope for finding a train running Paris to Strasbourg at some time on the 28th if our reserved train is struck. Similar situation for other reservations in May.
Sounds like if you have a non-refundable ticket to Annecy, yes you will have to eat it. Good luck with getting Chamonix to Paris tickets for May 2!