*mau: i would agree with chickselog with regards to the step 1 2 and 3's pricing, it won't cost you 3k to get all 3 of them and they are very much worth it.
Step 1 is basically a cleaner wax that you don't have to use every month, you only use step 1 when you notice your paint oxidize a bit and dull a bit, i use step one about 3 times a year on a car, i make it a point that every 4 months i use step 1, and sometimes i even pass on this step especially if you maintain your monthly waxing regimen, as for your problem about light paint i think its oxidation related problem, either that or you've had an overheat where the steam sort of cooked thru the paint, thats my project today BTW, i think step one would definitely improve its shine and with this one i again agree with chickselog that a picture would prove to be very helpful in determining what proper steps should be undertaken to improve the paints condition.
Step 2 is basically like a make up for paint, it masks all those scratches that you got in your paint, now if the whitish part you described has an uneven surface using step 2 might improve its shine even more since it seals and hides these defects. Also if the whitish part is uneven or was not removed by step 1, chances are you might want to use certain megs polish just to bring its color and shine back to life but most of the time step 1 and 2 can already improve oxidized paints conditions. If a single application of step 1 doesnt do that much try another application this time try to work the cleaner more thoroughly by applying a little more pressure, use microfiber cloth to avoid scratching and swirling
As for Step 3 try not to get the liquid version, although the liquid version is really a lot more easier to apply and easier to spread and cheaper, i would personally stick with the paste wax, it has a slightly noticeable deeper gloss and it lasts a little longer, also with paste wax you might think its expensive, but based on personal experience i can do about 2 bottles worth of cars with a can of the step 3 paste version in the end eventually saving you more i hope this helps
As for T-cut, i tried using it and yeah it does mask and help deepen the color of the paint, but after one wash *tadaan* its back to square one you're back to a dull paint, i would rather invest my money on a megs cleaner wax or a moms cleaner wax than these pigmented wax/polishes
As for frequency in applying the 3 step i apply step 1 every 4 months, just a little to remove dull paints, step 2 on the whole car, again just enough to cover swirls every 2 months and step 3 every month.
the 900 peso bottles are most probably from the reflections line and FX line, Reflections line is a 2 step process and both cost 900+ each advance wax and topcaot these are really nice on dark colored cars, if you are pressed for time and need a nearly instant fix, you could also try Moms FX its a one step product that delivers nice results its like step 1 2 and 3 performing just a little less, it can also clean your paint but since its cleaners are a bit mild im not sure if it can solve you paint problem, it can also mask hairline scratches and micro scratches, it has a nice durability although its shine is definitely more on reflective not wet look.
*chickselog: i really commend you for your fast reply and enthusiasm at helping other people, keep it up!