144 hour free transit. Flight with scales

In september I will fly from Madrid to Beijing with scale in Moscow. When I've tried to obtain de visa for China in Madrid application center for China, they said me that for me is aplicable the free transit of 72 hours in Beijing because I have other flight form Beijing to Ulan Ude four days later. But they said me that this should be confirmed with me air company, because this is a deal between air companys and chinese border police. I've called Aeroflot telephone number and they haven't any answer.

The general conditions of visa exception for 72 hours, say that this exception can't be apply for travelers with origin and destiny at the same country. But I don't know if this origin country, in my case, is Spain where I go, or is Russia where I'll stop in the escale