The bus from Tirano to Lugano is sold out

What is your travel date?
Right now, looks like you can take the train replacement bus from Tirano to Colico departing at 2:50 pm. It connects to the train to Monza, and there connecting to a train to Lugano, arriving about 7 pm. Nice views of Lake Como from Colico to Lecco.

Thank you for your reply. Our travel date is September 26
Where do we buy the tickets?

You are in luck. The rail construction will be completed by September, so you can get a train direct from Tirano to Monza. If you are on the Bernina Express departing Chur at 8:28, you will arrive at Tirano at 12:49. Without the replacement bus, the train to Monza departs at 13:08. The Italian train station is just across the piazza from the RhB station, so you should have no problem making that train. Cost is 12 EUR and it arrives at Monza at 15:26. There is a regional train from there to Lugano departs at 15:53 and arrives at Lugano at 16:58, which is actually earlier than would get there on the bus. You cannot buy the ticket from Monza to Lugano on-line from Trenitalia or Trenord, probably because it is an international train. You can buy it from SBB for 13.60 CHF when it goes on sale 30 days in advance.

I would just buy the Tirano - Lugano via Monza ticket at the station in Chur before hand. Or otherwise in Tirano...

Thank you for. your. responses.. Very helpful!