Great info... I'm looking at Paris - Mainz next month... Just wondering how easy it is to get Thayls tickets at station in Paris all the way thru to Mainz or does one have to purchase Koln - Mainz ticket at Koln Hbf after arriving there?

A lot of recommendations to buy thru Thayls online... Except can't get the Koln - Mainz leg from there website. Any other recommendations apptreciated!!!