All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ʻalayhi wa sallam, is His slave and Messenger.
It is permissible to transfer the money from one account to another via mobile or any other means. It is a lawful service and it is allowable to offer this service in return for a compensation. This has nothing to do with interest as long as the money is being transferred from the client's balance.
Hence, there is no harm in working in this company as long as its specialization is electronic money transfer, as stated in the question.
As for the user, you have stated that all the transactions are deducted from his debit account and accordingly there is no meaning for this condition in this regard because the transfer has nothing to do with the user's dealing with the bank; the money is transferred from the balance already available in his bank account.
In any case, if there is any prohibited condition in a contract, it is impermissible to accept or engage in such a contract. Shaykh Ibn ʻUthaymeen wrote, “It is impermissible to partake in defective contracts or those containing defective conditions...”
Allaah knows best.