Mango sees simple SMS informing flight changes as adequate and proper communication- Terrible service

I booked a flight at Mango Ref no TQPVLX to depart 18:40 20 Jan 2021. When getting to the airport before 18:00 they said I am too late the flight has already departed. I called in on 21/01/2021 at 8am only to be told they sent an sms on 15 Jan to inform all passengers that the flight has been pushed forward to 18:00, have they ever consider that sms get spammed by 100's of sms's a month how can just a simple sms be adequate communication. I have lost R1511.96. SMS boxes are spammed with Marketing, how can just a simple SMS that does not even show headlines senders info etc to pull passengers attention suffice and be seen as proper communication to inform passengers of IMPORTANT info on time changes. So disappointed, that is just it! they sent a simple SMS you have lost your money, no phone call no email just an SMS inbetween 10s and 20s of other marketing sms's. WHAT A ******* Whoever is in charge at informing passengers of time changes which I understand will happen needs to SERIOUSLY relook their processes how can you say an sms if adequate!! Everyone is feeling the effects of COVID not just the airlines!!