To warm the batteries, set a departure time. In that menu, you have the option of also preconditioning the cabin. If you use climatize now, all you get is the cabin. Note, depending on the actual temperatures, it may take 3+ hours for the batteries to come up to temp. It doesn't start preconditioning the cabin until about 20-30 minutes before your departure time. Setting a departure time is the only way to delay preconditioning the cabin.
They absolutely ARE charging for the service! For the first few i3 model years, they bundled 10 years of the remote service into the purchase price, along with 3 years of the in-car smartphone app enhancements that cost me $50/year to renew. Later models shortened the 10 year deal down to something like 3 years (I can't find the web page at the moment). Assuming that the 3G/4G network BMW is using still works, you will be able to renew for additional years if you pay them more. Big assumption, since a lot of 2013 and earlier drivers were cut off from telematics forever when the 2G network was shut down.....
Yeah, it's kind of mind-boggling - in our 'connected' world, an app that could be a real enhancement to BMW car ownership, instead is a total boat-anchor that they just seem to ignore.but it seems likely that it's just a crappy service/app that BMW really doesn't care enough about to fix.
Can you lock and unlock the doors, sound the horn and flash the lights? Because these commands use the same URL (and therefore the same BMW server). If those other commands go thru, you're able to send data to BMW, they do their thing, they send it to the car, car does its thing and responds to server and server reports success (or timeout or whatever) back to your app.