Dolomites in September end using public transport

Question

I am planning a 4 day trip to Dolomites, 2 days near Cortina d'Ampezzo and 2 days in Val Gardena in September end (25 - 28 Sep).

I mainly plan to do these hikes:

1. Lago di Braies, Lago di Sorapis and Tre Cime di Lavaredo which lies near Dobbiaco

AND

2. Seiser de Alm, Lago di Carezza and Seceda which lies near Val Gardena.

But my only problem is I will NOT be able to rent a car since my license is less than 1 year old. So, either

1. there is any agency that can rent me car without having the age of license rule

   OR

2. I rely on public transport around Cortina and Ortisei. I have heard about a bus 444 but I am not really sure if it can go to all places I mentioned above.

Can someone please advise me if public transport will be good in September end for me to enjoy my hikes and not the hassle of traveling a lot? This is my first time in Dolomites, so I don't want to spoil my fun without a car.

I am really worried if I can enjoy Dolomites in 4 days using public transport.