I’ve found that you have to be careful which AliExpress sellers you use. Some are just very slow to send their products and some actually misrepresent their products. The melting problem may have been due to receiving a low-density PE (polyethylene) mold instead of the PC (polycarbonate) type.
You also get better prices when using the mobile app instead of the website.
Most of the better PC molds seem to be made by Shunda, with a few stores offering rebranded boxes. I’ve ordered a bunch of molds from the “Dcrt pastry tools store” and they work well. The quality is quite good, but I have received the occasional one with a poor finish, especially on the edges (I used emery paper to cleanup excess plastic on the upper surface that would have been curled off using my scraper).
Searching for “polycarbonate chocolate mold” will avoid most of the silicon ones. “pc chocolate mold” is also a good filter. If you want dome molds add “2124B” to the search; these are the larger size (29mm, 11-13g/⅓ oz), similar to a CW2116/2295 but at a limited number of stores. The “2124” (no B) is available from more stores but is smaller (8g/¼ oz) size (I like these for liquid centers).