I think you need to seek legal advice, they will know what to do and the process of reversing it, if that is possible, otherwise you may need to do a change of name again back to the original? I'm not sure but good luck. You don't like the new name?
actually you don't have to pay to change your name, you just need to pay to get your new passport, everything else is free, and the easiest way would be to change it back via deed poll, which just needs to state your current name and the name you want to go by in the future, and then has two spaces for witness signatures saying its not for any illegal purposes. no paying necessary