Hisense malfunctioning oven timer

A few weeks ago I had complained about a Hisense stove that I bought from Makro. I had been struggling to get someone to look at the stove and check what the problem was with the oven. After struggling to get my the stove looked at by one of their technicians, with Makro referring my issue to Hisense and Hisense refusing to send a technician, we were finally contacted by one of their technicians who came to look at the stove. He discovered that the oven timer on the stove is malfunctioning causing the oven not to heat up. This apparently was a problem he'd encountered before on another Hisense stove. He went on to explain that he would order a new timer for the stove. Now after waiting almost 3 weeks for the timer, the technician has informed us that there seems to be a problem with getting the timer ordered and that if this part was unavailable, Hisense would have to replace the stove. He promised to get his supervisor to contact me which has not happened. I have spoken with the Technician as recent as yesterday with him still promising to either call me back after checking with his supervisor on what the issue is with the "ordered" timer is and promised that either he would call me back or his supervisor would. Today, he is not taking my call. I am honestly at my wits end with this Hisense stove that has stopped working.