Appalling after sales service

I had purchased a second hand (Sansui Double din car dvd player )on Saturday 25 April 2015 and installed it on the 28 April 2015 at my work. I am the Maintenance foreman in charge of all electronic and Mechanical issues (trade tested in both trades). It turns out that no modifications to the original wiring to the unit or my vehicle would be needed as it was a plug and play fit. the unit powered up fine and some functions worked however the touch screen was faulty and only registered touches at specific points. i immediately called the branch and was told to bring it back. I returned to the branch still with the unit installed. I took the stores personel in charge of repairs (MUSA) and proceeded to show him the fault. He confirmed it was faulty so i removed the unit. He said it will be sent out to their repair centre and he would get back to me by Thursday 7 May to let me know what the progress was. I did not receive a call back so on Friday 8 May i called and he told me he had not got any feedback so he didnt feel it necessary to call me. He then told me that his manager would call me shortly and as of today 13 May I still have not been contacted. Appalling service.