After migration from sprint

I just had a very frustrating, non-productive chat at the Sprint side of this debacle. We upgraded our sim cards to T-Mobile and got the whole "Welcome to the T-Mobile network" email. I found a plan we really like on the T-Mobile page but when I tried to change our plan it acted like I wasn't a customer. So, I opened chat and was told I needed to use Sprint chat. During that chat to find out what was going on, I was told that we need to migrate our account over to T-Mobile before we could take advantage of anything they offer. However, in order to do that we either need to take our phones into a brick and mortar store (50+ miles away) or contact "Migration Services" by phone with who knows how much of a wait (I gave up after 30 minutes.) I seems like this should be something that can be accomplished from our account page. We are now just considering bagging our account and going with another carrier.