Atonement for Profaning Shabbos

A pair of religious women underwent a serious trauma and needed a soothing atmosphere to recover. It was recommended that they travel to a Swiss resort for their health. While there, the atmosphere was so relaxing that they lost track of the days and miscalculated when Shabbos was due to arrive. On the day they mistakenly thought was Friday but was actually Shabbos, they did many prohibited labors. It was only when they were about to light candles before sunset that they had a feeling that they might have made an error. After a few minutes of checking, they realized they had miscalculated—they were horrified to find that they had accidentally disregarded Shabbos.
They knew enough to recite the text of the korban chatas and did so straight away, but they wished to know what else they could do to atone for their terrible mistake. Fasting is not suggested in any event nowadays since people are so weak. And, obviously, in this particular case, their poor health precluded any fasting at all. Giving money to tzedakah in lieu of the fasts was also not feasible for them since they were both of severely limited means. When they consulted with Rav Yitzchak Zilberstein, shlit”a, he ruled that they organize and attend shiurim in the halachos of Shabbos to atone for their inadvertent error.
Similarly, when HaRav Yosef Shalom Eliyashiv, shlit”a, was consulted by a man who accidentally placed a cooked dish on an uncovered burner on Shabbos, he ruled that this man should learn hilchos Shabbos to atone his sin. Since these women had violated an entire Shabbos, Rav Zilberstein required them to go one step further and organize shiurim to help others learn the halachos so that Shabbos observance would be maximized further as an appropriate atonement.