Wrong SFE amount help

Hi all,
I'm struggling to get a straight answer from SFE about the amount of maintenance loan I should be receiving. I have applied and received confirmation from SFE but it's significantly less than what the calculator on their website said and as it stands, it doesn't even cover my rent. I believe that they've calculated my amount while assuming that I will be living at home with parents, since the amount you get depends on 1. household income 2. residence at the start of the course. I have stated in my application that I will not be living at home, and when talking to several SFE staff on the phone I got different answers each time. The first answer I got was that I'm getting less than what I should because I'm currently living with parents and thus should submit a change in circumstances form once I get the details of my accommodation, which would lead to my application being re-evaluated. Today, however, I was told that SFE only assesses applications based on household income and so the amount I've been approved for is all I'm going to get. My parents will not be able to help me with rent as my maintenance loan is significantly less than the cheapest accommodation at my uni, so I am quite worried that I won't be able to afford to go to university. I'm going to Oxbridge, so I won't be able to work during my course as it's against the rules. Have you faced a similar situation? Please let me know how to get through to SFE effectively if you have any information.