4k = 3k year end rebate + 1k SA discount, depending on the area where you're at, SA discount can give up to 1.5 > 1.7k

free tinting as in give you a voucher of RMx amount or tint whole car for you ?
and, with what film, what brand, the heat rejection percentage, the thickness, and the safety feature of the film

can ask for full tank fuel, smart tag, etc...

well, he can tell you that he's giving 3m film in front of you and the next thing you know, the tinting guy is sticking on the cheapest film for your car, and the best thing is, you'll never know, so, your choice 

window visor cost 120 > 150+-, camera + HU (depending on your car's spec) cost 750 > 2k+- ,  i doubt the sa will give it to you for free

as a car owner, you'll learn this sooner or later, so, might as well as do your research to avoid being played around