Getting international roaming charges with the Magenta Plan in a country with free unlimited data

Wife and I have been in Japan for a week using the “Free Unlimited Data” which is clearly part of our Magenta plan.  We had gotten a text message from T-Mobile when arriving verifying that we could enjoy our free unlimited data in Japan.  Suddenly today we got a text message from T-Mobile saying that our international roaming charges were up to $50.  An hour later we got a message saying that they were now $100.  We panicked and turned off cellular data until we could get to the hotel and call T-Mobile.  The support person said that we now owed $150.  First she said it was because Japan was not covered in unlimited data, but I pointed out that the web site said otherwise.  She went away and came back and said that the charges were there because we did not turn off “Data Roaming”.  What??  The T-Mobile International checklist says to insure that data roaming is turned on!  She told us she could remove the charges if we bought the $50 30-day International data plan on one of our two phones, and that we should turn off data roaming on the other phone.  Her English was not great and I could not get a good explanation out of her as to why we needed to have data roaming turned off when the plan touted in Japan free data roaming.  Every time I asked her something she would have to put me on hold to go ask someone else.  We finally  agreed to pay the $50 in order to have the $150 removed.  After the transaction was complete she advised me to turn off data roaming on both phones.  So we did all of this, and now my phone, supposedly with the new $50 plan and with Cellular Data on and Data Roaming off, will not make a cellular data connection at all.  My wife’s phone without the $50 plan and with the same cellular settings (data on and roaming off) does make an LTE connection while standing right next to me and connected to the same cell network.  I searched the T-Mobile web site and there is NO indication anywhere that we have to turn off data roaming with the unlimited international plans.  I’m very confused and I don’t want to spend another hour of my vacation on the phone with T-Mobile, but I need data for maps, texting, and local information.  Can any one explain this?  Thanks.