try hunting for iPhone 6S used bro. I got mine 6S Plus 64GB for RM2300 complete set 

are they replacing the battery or changing it for a refurbish unit? not acceptable to take 3-5 days to diagnose. 

i have a bad feeling about this.

if they replace the battery unit, i hope they do it properly as i do not like to have my phone back with a wobbling screen. I have a bad experience of this situation previously.

if they change it for a refurbish unit, i hope that the one i will get is a good one. not faulty (i.e., yellowish screen, storage problem etc etc)

I am thinking of switching to a new phone instead of having to deal with wobbling screen or faulty unit after this process.

hmmmm

i have had the problem with battery for several times in the last 1-2 months. less than 20 % and a sudden shutoff. turn it on back again, the battery left around 20% but shutoff again in seconds.

bought my phone november last year.