MP credit with name in wrong field?

I recently traveled from the US to Brazil. The travel arrangements were made by a travel agent in Brazil. I received a confirmation and it looked good so it was ticketed.
As it turns out, the travel agent had entered my middle name and last name together in the last name field. (My first name was correctly entered in the first name field.) (I think it is common in South America for people to have two last names consisting of the maternal and paternal last names and that may have been the source of the error.)
Anyway, I had trouble checking in online since the search for my last name came up blank. At the airport, they were able to find my reservation and issue boarding passes.
I traveled to Brazil and back with no problems from TSA or Brazil immigration since the names on my reservation matched the names on my passport and visa.
The problem is that United won't issued MP credit for the trip. My MP account lists my first, middle and last names but they don't exactly match the reservation since the reservation listed my middle name and last name together in the "last name" field.
Any ideas on how to get credit for this?
I've called and talked to them and filed a request explaining the situation but they are stonewalling.