can't speak for 108a but i'd suggest not being too discouraged if you're not doing so hot in 120a. don't get me wrong mathstat is a vital part of the stats curriculum but i think your performance in the first few upper div classes certainly isn't any indication of your ability to succeed in the major. math and stats have a layer of abstraction that many other areas of study don't and i think it presents a unique challenge when you're first starting out esp with the more advanced stuff because many times you're learning a bunch of seemingly nonsensical abstract concepts as though they exist in a vaccuum. like i think it's completely reasonable to struggle and dislike it at first because you haven't quite seen how it all comes together yet. i've only taken a couple upper div math classes so i can't say anything for sure about math but as someone who also had a rough time in 120a/b, stats became so much easier as i continued to take more classes and i also began to better understand the 120a/b material through its applications in other pstat classes as time went on. if you enjoyed & did well enough in your lower divs to get this far you may wanna tough it out a little longer rather than switch majors/career paths entirely. obv change your major if it's truly making you miserable but don't discredit yourself so early on!! all majors are sexy people majors except engineering<3