If the Respondent fails or refuses to complete the Acknowledgement of Service then you will need to prove to the court that they have received the Petition and are choosing to ignore it. In the first instance you may be required to send a further set of the divorce papers to the Respondent by recorded delivery or by arranging for someone to deliver the papers to them personally, such as the court bailiff or a process server. If this fails you may need to consider asking the court to make an order specifying how further alternative or substituted service is to be effected. In exceptional circumstances, where all other service methods have been exhausted, it may be possible to ask the court to dispense with service altogether so that you can proceed to the next stage of the divorce despite the Acknowledgment of Service not having been completed or returned. Your divorce costs are very likely to increase if the Respondent does not cooperate with completion and return of the Acknowledgment of Service. If the petition is based on adultery or 2 years’ separation and consent the absence of an Acknowledgment of Service will make it difficult to proceed with the divorce.