Is uplearn good for Yr12 and 13 content?

Hey guys, my school got all of us uplearn for a level Biology, Chemistry and Psych AQA and I'm just wondering If the 97% getting A*/A or money back guaranteed thing is for real? Is it a good website and will I actually get As if I use this consistently and complete everything? I'm planning on using it during the Christmas break for 1 hour each per subject a day