Complain about the X1 BMW

I bought use BMW X1 2011 in 2018,In January 2019 it stuck due to rain water damage the repair cost R35 000 because the water damaged the computer box. Now in December i am encountering the same problem as the mechanic just diagnosed that computer-box is damaged due to rain water the .This meas i need to pay other 35 000 which i believe is not fair for me to keep on paying for the same problem.Why BMW make this kind of design and now we are stuck with the problem.