SARS is reaping poor people off

Please assist, on 2013 it was my first time submitting tax returns online on the portal, i did not understand most of the things, the questions that i was supposed to answer regarding medical aid, travel allowance and all those questions. After i submitted the results came out as i owed SARS R3990 of which i did not understand, i then immediately called SARS and i told them and an Agent assisted me and we did another filling which was correct and the results were R0.00( i didnt owe SARS anything). Later on SARS said for the first the returns that i made an error on i must pay them R12000 which they said it was 200% penalty on 2015. Today they say i owe them R15000. i left the job that i was working for and i had a provident fund package and all the money was taken to SARS. Please can you assist me.

Please help me dispute this amount,