～てさしあげる is a polite and humble expression, so it's not suitable for use with someone of equal or lower social standing. Instead, use ～てあげる or ～てくださる, which are more casual and polite expressions.

～てさしあげる implies that you are doing something for someone else, so it's not suitable when the other person didn't ask for help. Instead, use a different expression, such as どういたしまして, which acknowledges their gratitude.

～てさしあげる is a formal and polite expression, so it's not suitable for use in informal situations. Instead, use a more casual expression, such as ～てあげる, which is more suitable for everyday conversations.