Hampson has had a ton of negative comments all over the net.

Of all the chains they are probably one of the worst offenders for not honoring their commitments.

Good luck with the legal system.

A couple of other tactics to consider. Just ideas please consider the possible consequences before you act.

One, wait for a busy Saturday or Sunday and throw a fit in there front office. Demand your money, be loud and in their face. The embarrassment can cause them to get everything sorted out in a hurry. It helps if you can speak some Chinese, or better take a couple of people with you.
Do this after you get your relaease letter.

Two, do the same thing but invite the press along. News organizations are always looking for "stories" that they can report. Explain that you think the reason they are not paying you is because they are going bankrupt. Must be a misunderstanding. Once that makes the local news they will be spending a lot more than your salary to cover the PR disaster.

Just a couple of ideas.