After a month or two of bus replacements, Chamonix's train the Mont Blanc Express, will start running again on Saturday 24th June 2017.
Rumours about there being additional trains every half hour are true, but only in part, with an increased afternoon service on the new timetables.
Take note though, these additional trains don't run the entire length of the route, and they don't run until the end of the day.
Take a look at the summer 2017 train timetables and look for the new afternoon service in pale green highlights.
The summer service operates from 24th June to 17th September 2017.