Mick787 said:
Do I assume correctly that BMW won't react to such reports?
I think your problem is due to buggy system software, but maybe using iRemote, or whatever the BMW i3 smartphone app is called in the U.K., is part of the problem. If you set the low-cost charging period and departure time using iDrive in your i3, do the low-cost start and end times remain as set and does low-cost charging work as expected? If not, buggy system software is likely to blame. If so, iRemote and/or BMW's servers that link iRemote to your i3 might be to blame.
If iRemote and/or BMW's servers are to blame, there's not much you can do but complain until BMW fixes the problem.
If your i3's system software seems to be the cause of the problem, determine the system software version. If it is an older version, maybe the problem is fixed in the current version which you could ask your dealer to install under warranty to fix the low-cost charging problem.
Unfortunately, the system software version isn't displayed in iDrive. You'd need to back up your driver profiles to a USB drive using iDrive (handy to do before taking an i3 to a dealer in case a software update is performed that could erase driver profiles). Then open the driver profile text file in a text editor on your computer. The value of the <i-step> tag in this text file is the system software version. The entry in the backup file for our i3 is:
<i-step>I001-16-07-506</i-step>
The initial 4 characters signify an i3. "16-07" is the system software version date, July, 2016, in our case. The final 3 digits are some sort of subversion number that might be different for REx vs. BEV, maybe differs depending on market (e.g., U.S. vs. U.K.), or maybe is just a minor version number within the July, 2016, version.