Aston uni assignment non sub

Hi I'm in my 1st yr at Aston n missed 2 assignment submissions. I couldn't get medical evidence but sent a load of previous evidence relating to my issue however it didn't get accepted. Now I've been told in a confusing email that because the 2 modules are 30 credits I may have to redo the year?!! Both modules have 3 assignments and I missed 1/3 for both so surely I could just retake them in the summer? Please help me I don't know what to do and do not want to resit the entire year! The email said I can only take up to 45 credits in the summer but surely that's if there's1 assignment for 100% of a module?