If they wont fix it at this stage then your only option may be to stick with the physio. My experience of multiple ligament ruptures is that it does not matter how strong you get all the stabilising and mobilising muscles the joint is still unstable when activity levels are increased.

Generally when I have had trouble not being able to access surgery for this type of injury we have just worked hard on reducing swelling, regaining full movement, stabilising as much as we can...working glut, trans abdominals etc as well as major knee muscles. Often functionally a brace is required to prevent collapsing of the joint and further injury.

Using functional markers / outcome measures with your physio will give you a good idea of where you are at now...repeat these maybe monthly and thus when you see the surgeon again you can show them what progress you have (or have not) made. This will give them an idea of how motivated you are, what problems you are still having etc...and thus how much you would benefit from surgery.

Good luck