Hi, thanks for your post. It depends on the reason for making an appeal - if you want to raise a technical issue, please email students@accaglobal.com and one of the support team will be able to advise.
If you are referring to exam results, please note that ACCA does not offer a re-marking service. We do offer an administrative service - see our linked page here - but this does not apply to on-demand CBEs.
Hope that helps!