CMA Study Group

Hi

I just want to ask how can i switch from part 1 to part 2 for the exams i mistakenly paid fees for part one but i was to give exam for part 2 and when i was going to fill up for prometric then i noticed that by mistake i did this what should i do please help me out how can i do this switch? This is pretty expensive and i can't risk losing money over a small mistake 

Please help me out it is very urgent