You either pay the ETF or you wait out your contract.  Unless you can get someone to take over your contract (unless you have grandfathered unlimited this won't happen).  You signed a 2 year contract and got a phone at a subsidized price, this is part of the contract.  Without posting what sort of issues you are having its hard to say if they are at fault or if its the phone or you simply didn't do the research on how much you'd pay.  Be aware, you aren't really going to save much with another postpaid carrier.  I just got quotes from ATT, Sprint and T-Mo to see if they can beat my $165/mo after all taxes/fees for 2 smartphones and 1 dumbphone.  T-mobile was the only one who could but the REQUIRE that you do the payment plan so tack on another $25 per smartphone which actually brings their monthly payment for only TWO phones to more than my VZW bill. 

And bad customer service...  I've had nothing but good service for the 6 years I've been with them.  Not being able to have your way and get out of a contract YOU signed does not equal bad service, it equals them not feeling obligated to eat the $300+ of subsidies so you don't have to pay $600 for a new phone.