Hi, Ap1714. I think that practices in other universities may not matter terribly much in this case - my guess would be that your university is entitled to set its requirements where it feels appropriate. I would imagine that setting this requirement is partly to do with their agreements with other universities about the academic standard of the students they are receiving, and probably partly to do with not over-straining candidates who are already struggling. Study abroad can be very taxing!
Do you have a strong relationship with any of your lecturers so as to ask about what you could do about this (frustratingly small) gap between what you need and what you have? I think in this case a human connection is your best bet. Someone who knows you are a good, hardworking, committed student and who has confidence you will represent their institution well while abroad might be able to help you find a way to get what you want.