I am not familiar with Louisiana's regulations with regards to workers' compensation claims, but I am happy to provide you with general information. Look up the amount that should have been paid, and sent written documentation to the claims administrator, asking that it be reviewed. Double check that modifiers, CCI edits, etc. are all applied correctly before appealing to make sure that the claim submitted is correct.
I have appealed hundreds of California workers' compensation claims, and if you lay out the facts for the claims administrator in a clean, concise format with supporting documentation from the CPT manual, ICD-9 manual, or official fee schedule guidelines and asking them to review a specific line item, denial, etc., your chances of success are much higher than sending a "generic" letter requesting a review.
Good luck!