Is a verbal contract enforceable? The following complaint has been filed with BBB, FCC, FTC, State AG & State PUC

AT&T claims I owe about 1100 dollars in long distance charges for 1 month. To support this, they claim they had verbal agreement to charge me at the highest possible rate for international calls related to a botched U-Verse installation. I claim there was never such an agreement.

In trying to resolve this with AT&T, they agreed verbally to my consultative services for which I invoiced them about 3,500 dollars. The AT&T representative involved now claims there was no such verbal agreement.

AT&T twice sent their initial billing to collection, to which I responded with cease & desist letters. I also sent my accounting to debt collection. AT&T subsequently lowered the amount to about 440 dollars without explanation and re-initiated their debt collection activites.