Inferior Service Delivery

A little over a month ago I was told to bring my car into any Audi Center to upgrade my heater element as it was affected by some sort of technical fault. I promptly booked it into Audi Fourways for the day. I was called later in the day to be told that my car was ready, however when I got there, it was far from finished. I was told that it had to left overnight (what an inconvenience for me). I had no choice but to leave it there for a second day. They called me again on day 2 to say they have fixed everything, and all is in order. Fast-forward to two weeks ago, when I noticed that, (1) One of the vents on my console is no expelling air, and (2) the hot air took forever to come through (over 45 minutes). I logged a complaint with them, and over a week went by without any kind of assistance or resolution. On the second week I was told to bring it through this past Saturday (08-09-2018) to resolve. Which I did. And guess what; I'm still having the same issue. The fact the 'work' was done in under 1 1/2 hours leads me to believe that either 'fix' is inadequate, or was never implemented. I will be escalating his further as well.