incompetent
adjective
uk/ɪnˈkɒmpɪtənt/ uslacking the skills or knowledge to do a job or perform an action correctly or to a satisfactory standard:
Her performance was deemed grossly incompetent, so she was fired.
utterly/completely/hopelessly incompetent
Incompetent handling of the contract left us exposed for millions in unexpected insurance obligations.
incompetently
adverb
To win the case, they have to show that the Bank acted incompetently.