Inconsistancy in SARS

for the past couple of years doing my tax return on e-filing i had no issues , i work for the same company , drive the same car , doing the same job , the Company i work for have a contract with Avis Fleet and rent cars from them for all employees working for the company ,SARS rejected my business milage for the tax year 2017/2018 which they never done before , SARS said that the car is not in my name which is registered to Avis , i gave them the Avis Contract and a letter from the Company saying that I used the car with the registration no for business and personal use, we have a specific person that sign the proxy for all cars , my e-filing was done in June 2018 and haven't heard from SARS since , i received a statement from them on the 14/01/19 with penalties for late payment , i did 48000km business miles which was ignored. when someone owes SARS money they are very quick to send you a summons but when they owe you money it can take forever , i believe the people that do the assesments for SARS are not qualified to do that work , why will there be a problem now when the past couple of years all was in order when nothing has changed, i really don't understand how SARS can change from one year to something different the following year.