sprint
the only reason i still have my service is because my work offers a 23% discount....HOWEVER my fiancés account is always getting messed around with...
first time, they changed his plan without him requesting it and he only noticed because the bill doubled

he NEVER authorized a change ... this took about 4 calls to get "fixed"
next time, they never credited the money they charged for the first boo boo above...this took another 2 calls
most recent, they shipped him THREE BRAND NEW PHONES...he was like wth!?!?!?!? so he calls and
THEY ADDED ON TWO MORE PHONES TO HIS ACCOUNT 
... finally a nicer CS rep said that someone was probably trying to "pad" their monthly sales and just added these new lines on to his account...they said they would fix his account (credit the money they charged for the extra lines) when he sent the phones back....we were like NO you WILL CREDIT US NOW and send us a prepaid label to send the phones back!!!

... this fiasco took us two days worth of calls...we lost track of the number of people we talked to
sprint!!!