I apologize for any frustration this may have caused you. I have forwarded your concerns to my superior.
Indeed, whenever a vps is canceled, it's going to automatically move any user data to their next default server. If you have another vps, it will likely be moved there. If you delete your vps users before canceling, as you attempted, it may still mention moving the data but won't really have nothing to move. So, that is still an option for you if you don't want any data moved. We also do not allow duplicate usernames, regardless of what server you're on. That way, when we do need to move users to another server, it should not cause any issues for existing users.
We're sorry to hear of the trouble, though, and would be glad to investigate if needed. We're also sorry for any confusion; it does normally take a few days for a vps to be deleted completely.
Please let us know if you have any more concerns or would like us to look into anything.