The same thing has happened to us.  Now they don't have the promotion in the new agreement for the $400 off the iPhone X.  It is a mess trying to get anyone to call or answer me.  But yet they want me to sign the new agreement without the $400 promotion in it (the first agreement had it clearly listed that we would get $16.66 credited a month for 24 months).  I am furious and have waisted a lot of time on this already.