OK, my experiences.
Full throttle - very good for buying accessories and gear. Do not buy things like tyres or batteries from them. Do not let them touch your bike, they will f it up.
Suzuki Clown Store (Centurion) - I bought all my OE oil filters and fork seals, etc from them. I did all work on my bike myself. Do not let them touch your bike, they will f it up. They cannot even fit and balance a tyre properly, and they like revving the crap out of customer bikes first thing in the morning (I saw this first hand and was dismissed as a fool when I told them that is unacceptable behavior)
For tyres - I can ONLY recommend Just bike Tyre in Centurion (in same complex as Yamaha). Great prices and I have only ever had good service from them, they will not f up your bike.
So, in summary - If you want your bike to last, service and maintain it yourself with genuine parts. Learn to do these things yourself, it is MUCH cheaper and you have a better idea what is going on.
Also, when buying parts (and accessories) I have always imported unless timing/availability meant I had to buy local. You will end up paying less if you import on most occasions.
I did not replace my K7 GSX-R1000 with another Suzuki because of the pathetic dealers. I had a similarly crap experience with Kawasaki.
I have since bought a BMW, but I cannot comment on their service department yet.