There is no specific right to withhold payment pending an itemized invoice, unless the contract/service agreement provided for this right in some way (e.g. it was a term of the contract that you be provided an itemized invoice).If you believe you are being overcharged and cannot work it out, then you might pay any amount(s) which are not in dispute--and see if the contractor will take you to court for the disputed balance. Only do this if you truly, in good faith, believe you are being overcharged--a mere absence of an itemized invoice is not enough.