In the years I've been around, I've seen lots of supervisors transferred to jobs and locations that they did not like at all. Some bit the bullet and outlasted the unpleasant job change, some moved on. Some transfers were punishment for misdeeds, and some were rewards for achievement, yet the reason for the transfer had very little to do with how much the individual liked the new assignment.
I knew a guy who was promoted from that wretched "on car sup" job to a center manager job in a part of the state that neither he nor his wife enjoyed at all. He asked to go back to his old "on car" job at his old center, and even volunteered to run the preload at the center he was at before ours. They said, no dice, you will stay in that hellhole until we decide to move you. He resigned.
When you entered management you should have realized that your job assignments may change. You don't work on a negotiated contract, so your salary, as well, is determined by the company.
Everything about your plight is part of being a supervisor or manager at UPS. You need to understand that clearly, or leave.