Annulment of Delaying the End of Yom Kippur — While Standing

Throughout the year I am stringent to end Shabbat according to the opinion of Rabbeinu Tam, and on Yom Kippur as well I end the fast according to the time of Rabbeinu Tam. This year, because of weakness, at the end of Ma'ariv on the night after the fast I asked three friends in the yeshiva to perform hatarat nedarim for me regarding my adherence to the time of Rabbeinu Tam, and I said that had I known I would be this weak, I would not have accepted this upon myself. They said to me three times: "It is permitted to you," but they performed the annulment while standing. After that I ate before the time of Rabbeinu Tam.

A. Did the annulment of the vow take effect?
B. If the annulment did not take effect, is someone who eats before the time of Rabbeinu Tam considered to have eaten on Yom Kippur?

Shalom u'vracha 

A. Any annulment that is based on regret from the outset may be done while standing. 

B. One who eats during Rabbeinu Tam’s time, and did not accept upon himself the time of Rabbeinu Tam as binding, but only as a “stringency” and not as the law, [as you wrote in the question, “I am stringent”], is considered to have violated a stringency, not a prohibition. 

In general, regarding a “good practice that one followed three times” without stating it in the language of a vow, the declaration made after hatarat nedarim on Erev Rosh Hashanah is effective, and there is no need for hatarat nedarim. 

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