ur car is flx or fl?

FLX rear lights are LED, so if 1 side not working is the LED driver inside the light assembly problem. Your other side of the brake light and 3rd brake light still works?

Mine also happen like u. I go accs shop at kampar, they open the board in lamp, blow a little bit and it works like new again. Rm 20 only. If change board rm 80

Not sure the right way to describe, I usually pull up 45° to remove it with the cable attached to the bulb to assist removing.

However I feel installing d new one is not as easy as removing it.. almost the same way to install back just the opposite way..

removing is easy, just twist and pull. installing back depends on luck

dont pull out, pull up first. plug back the cable to the bulb, apply upward vertical force to the plug. the bulb will disengage from the hook/spring/holder. like pulling ur house main switch upward... ahaha

I once heard of cases like this where the brake tend to like drag the car forward. If i not mistaken, its ur crossmember bushing / arm bushing etc. Something related to handling thingy.

Take it as a 2cent opinion..im not really sure.

go visit sc
or give us your location, maybe can give some reliable workshop.

p/s: 100k+ mileage and never change brake pad (at least that what i suspect)

It is a lot of work. You basically servicing CVT + Timing belt / Water pump + Tensioner. Check the service manual to see if they all have to be done at one go. This way you may able to delay some the spending (but you may pay more for labor later). 

Is the workshop using Proton original parts or OEM? If original, maybe it worth it. Proton parts are no longer affordable these days.

If you are DIY person, Air filter buy online generic brand RM12, generic cabin AC filter RM10, waterpump last time i changed mine RM90-100 GMB brand; changed together with timing belt..
Coolant i bought Toyota Longlife from spareparts shop, RM25*2 + RM5 for 5L filtered water for flushing and dilution.
Valve cover gasket around RM100 parts+labour. Engine cap i buy online RM4 for the silicone rubber ring, use back existing original cap, pull out the harden rubber ring.
If your tensioner bearing is using black plastic roller, make sure the fan/V-belt is 6pk1669 NOT 6pk1677, 1677 too long, tensioner will spoilt faster..
Spark plug wise instead of normal cooper, i use NGK G-POWER platinum, bought from shop around RM60-65, install myself..haha

After replacing CVT fluid & CVT filter, oil leveling and Clutch adaptation for the cvt gearbox is a must.. if foreman say no need, think twice whether to proceed or not... if foreman said no issue one or conti car only need to do such steps, cabut cepat2....hahaha....
RM145 make sure the CVT filter is original from Proton or Punch powertrain...