Srilankan Airlines — cancel the booked ticket & provide another boarding pass with 5 hours delay

Address:

SriLankan Airlines Limited, C/o Translanka Air Travels Pvt Ltd., Hotel Femina Complex,14-C, Williams Road, Tiruchirappalli,Tamil Nadu 620001., Tiruchirappalli, Tamil Nadu, 620001

I travel sri lankan airlines from riyadh to trichy via columbo, incident happen in columbo airport 21st july 2019, i had complaint to srilankan airlines customer care but i didn't get any proper answer & compensation

I am rajaprabha thinakaran, my pnr number sxcwdb, i have booked the ticket riyadh to trichurapallytrz via colombo at 21st july ul266 & ul131, this is confirmed ticket also,
Case happened to me 22nd july in colombo was totally unacceptable, when i reached colombo srilankan airlines staff asked to stand separate who's are going trz ul131, so i am stand separate with other's, then srilankan airlines staffs collected from us the boarding pass which was issued to us in riyadh and given to us another boarding pass the flight was ul133, while that time staff said flight was technical issue so can't board, but later i came to know that due to over booked the ticket airlines was cancelled my tickets by themself,
We stand on there with another boarding pass ul131, then i move from there to see the ul131, there is ongoing final call after we reached 20 mints, so then i asked airlines staff put me in the ul131, i have a health issues that's why i going to india, please help me on this, but staff said not possible and we will call doctors for you, but until i was in the airport doctors didn't came to see me or airlines staff didn't take me to hospital or doctors,

This is how you are treating the passengers,

Here i am asking you that how airlines can cancelled my tickets without any prior information as per international civil aviation rules,
And then waiting time was almost 7 and half hours and didn't provided the proper service

As per international civil aviation rules there is delay due to airlines service then airlines must pay compensation to the passengers due to involuntarily pushing the passenger to another flight, if voluntarily passengers agreed to shift the flight then there is no issue, but srilankan airlines forced the passengers to shift to another flights without prior information, due to delay of flight i paid to taxi in india double the cost i booked and i faced severe vomit in srilankan, not given lunch,

So here i am asking to you that airlines must need to pay compensation for delay as per international civil aviation law,