I am having trouble with your timeline. Tell me if I understand it correctly.
September 2007 start service with Verizon on 2 year contract.
September 2010 end service with Verizon
September 2010 start service with T-mobile
September 2011 attempted to upgrade T-mobile phone. Upgrade failed. Stopped using T-mobile.
September 2011 reactivated old Verizon phone(SIM card?). Verizon store(official or reseller?) told you that you could use same plan you had before.
First I am curious as to the model of Verizon phone with a SIM card. Verizon is a CDMA operator and had very few SIM GSM/CDMA models for international operation.
September 2012 get bill from Verizon for ETF.
Is the timeline above correct or am I missing something?
There is the Verizon Direct Forum at »Verizon Direct
They might be able to help. I would advise getting the exact dates of the transactions or communications involved, the Verizon model phones involved, and anything else such as receipts or bills you have.