Upvote:4
If Singaporean Immigration did not explain why they refused him entry or give him the visa refusal reason(s) in writing, and you are certain he has a good travel history and has never breached immigration (or other) laws, there is little we can realistically suggest to help. Your best option is to seek advice from an Immigration lawyer. Having said that, it does seem unusual that nothing was provided in writing on either occasion. See Does being refused entry to Singapore mean I am now blacklisted?