Hi Bruno,

until last year there was no public transport via the Paso de San Francisco and I think it has not changed since. For crossing the border you may not need a DIFROL permit about the Tres Cruces NP I am not that sure. As I remember you can get the permit easily in the DIFROL agencies and even by fax or email and it is free. So ask for one and you are on the save side.

Paso de San Francisco is officially on Difrol's list, but I have never heard about anyone having the permit when crossing the pass.
http://www.difrol.cl/index5.htm
Tres Cruces is also listed on Difrol's page.
http://www.difrol.cl/0103.htm

I may have had bad luck when I applied for a permit from Difrol. I never got any response at all, got a bit miffed and climbed all peaks from Argentina instead.

No, no bus company. You need to go either via Santiago-Mendoza or Paso Jama (from San Pedro).
Agua Negra has no public transport either

There are some tourist services that will get you from Copiopa to the hot springs at Ojo base camp on the border, from there try to hitch a ride into fambiola.

Brunovcv wrote:Thanks all for your answers.
That's not a good news for us but at least we still have some time to find an alternative.
Do you know if it's easy to reach Fiambala with a collectivo or another transportation coming from the La Rioja aera?
Bruno

From La Rioja it's very easy to get to Fiambalá. There are buses all the way. Sometimes you have to change in Tinogasta, but there are direct ones as well.

Bruno, Did you do all 5 summits or just main?

I may be very wrong here, but...
Bruno; were you in the team which tried the traverse of the whole Pissis Massif?
I mean the team with Fernando.

I have heard that team didn't have any success.

Corax,
I sent you two PMs about this.