Cancelling and renewing work permit (extension possible?)

I am working out currently what my options are. I currently have about 2 weeks until I fly out of the country for a 1 week stay over the new year and arrive back in China on the day my current work visa is expiring.

Now I have the unfortunate problem of not getting the cancellation chop from my previous employer as he is hard to contact （didnt leave on bad terms but seems they are not bothered). Any good suggestions to extend the Z type for just a few more weeks/month so I can get this sorted out when I return? Also will it make it hard to renew my work permit with the new employer?