In all ages, God has wrought through holy angels for the succor and deliverance of his people. Celestial beings have taken an active part in the affairs of men. They have appeared clothed in garments that shone as the lightning; they have come as men, in the garb of wayfarers. Angels have appeared in human form to men of God. They have rested, as if weary, under the oaks at noon. They have accepted the hospitalities of human homes. They have acted as guides to benighted travelers. They have, with their own hands, kindled the fires of the altar. They have opened prison doors, and set free the servants of the Lord. Clothed with the panoply of Heaven, they came to roll away the stone from the Saviour's tomb. {GC88 631.2}

In the form of men, angels are often in the assemblies of the righteous, and they visit the assemblies of the wicked, as they went to Sodom, to make a record of their deeds, to determine whether they have passed the boundary of God's forbearance. The Lord delights in mercy; and for the sake of a few who really serve him, he restrains calamities, and prolongs the tranquillity of multitudes. Little do sinners against God realize that they are indebted for their own lives to the faithful few whom they delight to ridicule and oppress. {GC88 631.3}

Though the rulers of this world know it not, yet often in their councils angels have been spokesmen. Human eyes have looked upon them; human ears have listened to their appeals; human lips have opposed their suggestions and ridiculed their counsels; human hands have met them with insult and abuse. In the council hall and the court of justice, these heavenly messengers have shown an intimate acquaintance with human history; they have proved themselves better able to plead the cause of the oppressed than were their ablest and most eloquent defenders. They have defeated purposes and arrested evils that would have greatly retarded the work of God, and would have caused great suffering to his people. In the hour of peril and distress, “the angel of the Lord encampeth round about them that fear him, and delivereth them.” [Psalm 34:7.] {GC88 632.1}

When has this happened?

As angels wouldn't obviously manifest themselves as angels in such situations, we will not find any record of an angel doing that,

however, if EGW said it happened, or is happening, then God can take care of how it can happen in those circumstances.

By the way, my 2nd quote wasn't exactly the same as the 1st one.