Most disputes about fees are not ethical issues, but simple fee disputes. If you believe the lawyer actively did something unethical, i.e. purposely double billed, that could be an ethical issue.
Fee arbitration https://www.judiciary.state.nj.us/oae/fee_arb/fee_arb.htm
Ethics complaints https://www.judiciary.state.nj.us/oae/atty_disc/atty_disc.htm#filing
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The first thing before filing a complaint would be to meet with the lawyer to make sure you have a complete understanding of the billing.
The next thing is to discuss it with him/her if you dispute some charges.
Once that's resolved and you still have a dispute, Ms. Ellis has given a starting point.
Answering your question does not create an attorney-client relationship. Every case is different and a resolution depends on a thorough review of applicable facts and law. No attorney can guarantee a particular outcome or result.
As Philip suggested, sitting down to talk about what you think was done improperly typically goes a long way to help you understand (in some instances) that nothing improper was done - or if it begins with evasion and shady looking explanations, then your suspicions seem to hold water and you should pursue them.
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