I would gift the money to another city and abandon it. For me gifting works all the time - if done right. I think this is how it work (this way I get my money over as quick as possible):
- city A active, start sending gift to city B
- switch to city B - to be safe wait a minute or so before doing this. I assume when switching the gifting process is triggered in city B as well, also wait a little bit
- switch back to city A. In the regional view when clicking the gifting button you should now see a delivery truck with a § symbol leaving your town hall in city B driving to city A. It drives to town hall in city A to pick up the gift and drives back to town hall in city B. You can watch this.
- when the truck arrives back in city B I'm getting the message that the gift has been delivered
- switching then again to City B and after s short time you have your gift - done
By watching the money truck you might see if it gets stuck in the traffic which might be a reason why the gift is not transfered.
Hope that that helps!