Which law firm in Minhang District, Shanghai is more trustworthy?

I didn't say that unless you know this lawyer well.

The only feature of the lawyer I hired in Shanghai is that he speaks better than he blows.

Finally, it was decided that P was either cheating on lawyers' fees.

You don't need a lawyer to appeal directly. All you need is an iou to make him pay back the money. The well-documented court will certainly support you and then apply for a compulsory payment order.