We dont know the work of Dawah so There will be mistakes. The remedy of mistakes are seeking Allah forgiveness and dua and to continue the work. There is no use of discussing mistakes (of others).
If we will engage busy ourself in Gasht Taleem Mashwara Tashkeel Khidmat Ibadat Namaz at Night and Dua at Night Zikr of Allah then it will increase Ulfat Muhabbat between us and will also increase the work of Dawah
(Makatib Part 1 Page 111)