Is it valid for my husband to take me back after divorcing me via mobile phone, knowing that he had divorced me several times previously and we reconciled after giving charity, and that the last dispute was due to my communication with families to help me?

It is not possible to determine whether a divorce has occurred or not without knowing the exact wording and circumstances in which it happened, nor can the effect of a divorce be erased by giving charity. If the one who issued the fatwa to you is among the trusted scholars and you explained the situations to him accurately, then you may act upon his fatwa. It is not permissible to seek a divorce without a legitimate Islamic excuse, and it is forbidden for a woman to ask her husband for a divorce without distress. The husband has the right to take his wife back before the 'iddah (waiting period) ends, provided that this was not the third divorce. There is no sin in seeking help for necessities, provided that no forbidden act, such as private seclusion with a non-mahram, results from it. It is not permissible for the husband to accuse his wife without evidence nor to harm her with harsh words. It is forbidden to travel to and reside in lands of disbelief except under specific conditions, and the prohibition is intensified for a woman traveling without a mahram.