HELP: My colleague is a complete retard

Last April, a student from a non-target in London and I -English target- got accepted for an internship in a private debt shop. Recent fund and not much in AUM, but very talented team coming from ER in BBs and EBs, great potential. The shop has offered us a 2 months position outside of Europe, and we are to share a flat with one another, for some administrative BS. Anyway I get in contact with the other intern, whom we shall call Lana, to get a drink in London and meet each other. She's fun, tall, ambitious and we have a good time. After that we don't see each other before leaving for the internship. 

One day i receive a message from her asking if we can travel together because she's too scared and has never been on such a long journey or some BS like that -she is 2yrs older than me. So we do the X hrs flight together and Lana complains ALL the time; "it's too hot in the airport, too cold in the plane, seats too uncomfortable, visa queues too long...". When we arrive at the flat, she puts on this surrogate princess style and complains how it's not luxurious enough and that the company should have given us a better place (the flat is in a private area, floor 33, beautiful view, pool, gym... so more more than acceptable). Three days later, we start our first day at work and Lana's like totally lost. It's actually another level; she just doesn't understand anything. And still to this date -a bit more than a month since we started, the situation hasn't changed. For example, after being asked by a junior PM to look up some of our competitor's NAVs and prices, she goes 1h later to THE SENIOR PM to ask him how to search smth on the bloomberg terminal. More than once, she took a junior PM's entire morning or afternoon to have her explained (and eventually did) the research she had been assigned with. When she asks a question, the interlocutor ALWAYS has to invite her to repeat as it didn't make any sense. She took more than two working days to come up with a list of 3 FX rates' daily values in the past two years (values that can simply be exported to Excel, I imagine she copy pasted the values one by one LOL). In a fucking meeting she asked ONE OF THE FUCKING FOUNDING PARTNER IN FRONT OF A FUCKING CLIENT why our firm didn't accept LTV ratios of over 90% (we actually stop at 70%). The list is virtually endless and I've stopped to try and remember new events as it's getting more depressing than funny. 

I get the impression that her thought process is completely dispersed, and that she's not capable of following a logical chain of reasoning. And guys keep in mind that I share a flat with her, so this nonsensical nightmare doesn't stop at work -she lost my office AND flat keys, eats like a pig... Also when Lana's busy wasting time from our M+1, I obv can't go to him for any queries or debrief. 

idk what I should do to solve this situation (if even possible!)

However the positive aspect about it is that I get to look very good in comparison, I'm well integrated into the team and they're really happy about my work lol