If you are having difficulty getting answers, it might be a good idea to ask your ex to reply by a certain date. Give the ex a reasonable amount of time, like a week to reply. For example, "Please reply by Saturday October 13th." It is also best to always correspond via email rather than texts. If the issue is time sensitive and a week is not reasonable then it might be a good idea to state that clearly in the email and ask for a reply asap.