Did the phone and computer have something to do with your relapse? If not, it sounds punitive. But they are probably at wit's end trying to come up with something that works to help keep you sober.
Tell your mom what you told us. It's impacting your job. The two of you work out a plan that will allow you to be accountable. Is there something else you will "trade" for the phone privilage.
Perhaps it's time for them to get to an Al-anon meeting.