Honey_bee, when you say 'wont be able to do what he is asking', what do you mean? Do you mean that one month isn't enough time to complete the changes?
It would not be unusual to go over the stated timeframe in any research thesis. So to go into your third year, even if it is an MPhil, is not that unusual nor is it the end of the world. Many people do this in order to complete and pass their thesis, whether it be at Research Master's, MPHIL or PhD or Doctorate, and as Bilbo said, if you want this, then you need to make the changes. Bilbo is also absolutely right when she says that the supervisory panel's approval is not the same as your supervisor's. Your supervisor is trying to help you pass-whereas the panel were basically approving your plan and acknowledging that your results seemed sound.
But the thesis is not just the research or the results- a huge part of it is the writing, thinking and shaping of your work into a text-the thesis. So some of these steps that seem so hard and just unreasonable are actually important parts of the process that everyone goes through to some extent.
Can you have another chat with the supervisor, look at what needs to be done and then if it takes a bit longer than a month, negotiate an extension that is reasonable from both of your perspectives?