First, they cannot directly withdraw money except as  authorized by you, so if the terms under which you let them withdraw money only allowed them to withdraw for the regular monthly charges, not for a replacent phone, they could not do this. Review the terms of the agreement(s) or document(s) by which you authorized them to make withdrawals.Second, even if they could withdraw for a replacement phone, clearly, they could only do so if 1) you requested one; and 2) you actually received it--they cannot unilaterally decide to send you a new phone and charge you for it without your consent, and they cannot charge you for something you did not receive.If the charge was improper under one or more of the above, which seems to have effectively been acknowledged by them since they returned some of your money, they should have returned *all* of your money. If not, you could sue them (e.g. in small claims court) for the balance.