Jevgenij dropped me a comment about new firmware. It is from Telia Sweden and you can get it from here http://www.telia.se/privat/support/mobiltbredband/uppdaterausbmodemorouter#huaweib593formac=&tabMenu_0=huaweib593formac The direct download link is https://www.telia.se/dms/mgnl-ext-dms/www-telia-se-ui/installation-files/se_telia_r-m-h-s.tar/se_telia_r-m-h-s.tar.bz2 The firmware seems to have nice features, SMS and even to force for 2G-operation. He highly recommends this one. This looks very promising, perhaps I'll try this myself.
I upgraded my B593 with this one and can confirm that it works well. GUI-languages are: Svenska, Suomi, Pусский, Norsk, Dansk, Eesti, Lietuviu and Latviešu. No setup wizard. Has external antenna support. No VoIP. No DDNS. Mode selector has 5 options: auto, auto 3G/4g, 2G only, 3G only and 4G only. SMS in/out. No DLNA. So it is little bit light on features, but is fully exploitable and SP102!
The file will contain a SP102 for u-12. Altough The Exploit does not work, it seems to have a nice bug in it. When you're FTPing into it, it will open also SSH-port! Whaat! 
Warning:
SSH passwords are reset to something the telco set. However, USB/FTP-hack will work and you can get the /var/sshusers.cfg and look at the plaintext password from there.