Do you know how long this could be? Or any mail address where I could ask?

Nihao!
I'd be very pleased if you could help me with something.
I've been about 30 times in China due to my job, using the channel 24/144 hrs in Shanghai or Beijing. My company provide my tickets and I've always flown to Hong Kong as a final destination. But last December, we got an unexpected problem and I finished my trip in Shanghai (I made HKG-PVG-HKG) so they consider that was a round trip. They told me at immigration in PVG that I couldn't use the 24 hour channel for a while as a "minor infraction", not that much (and I could be back with a Chinese Visa, I'm not banned at all), but they never told me how long.

Maybe since december the fine period has expired, but I don't know, and I can't go and risk myself again.
I'm from Barcelona and at the consulate they told me to talk to immigration Shanghai but... how?
I'm a courier and I usually fly all over the world so I need to know about that.
What would you suggest me?
Thank you in advance, and have a good weekend!