That is BS. You aren't living there, you are visiting. You don't need to pay any rent. And $100 for a phone bill is excessive. A phone plan can easily cost $30-$50/mo, and if you finance a new phone then you'd have a $30-$40/mo bill on top of that for 2 years only. You should just get your own phone plan and instead visit your parents for a day, don't spend the night.