Need to make a formal complaint about Qatar Airways as I paid for a service that I didn't get.

What was that service you didn't get?

The Golden rule for flying is contingency planning. A plane can be delayed diverted or cancelled at any time. If it is critical that you have to get somewhere at a particular time then leave earlier and get there earlier. If you are transiting then choose airlines that have more connection options than an other airline so if there is a delay it will be for a less time. "to our horror the next flight was in 5 hours" - actually that is not bad! You should have known that this was the case as part of your planning. Also use all the flight tracking tools you can - Tripit, Flightradar24 flighttrack - knowledge is power! Monitor not only your plane but the inbound plane as well.

In this case i have little sympathy as you did not plan the trip properly.

In Athanasia's defense, this WASN'T some long-considered holiday trip. People often forget that when a death or compassionate issue occurs, time is regularly of the essence - and that includes booking time which is often minimal in nature. Stop for a minute to consider for instance that certain religions require burial services within a 24 hour period ~ and when you are half way around the world, this alone presents special challenges.

Airlines DO recognise this and many still provide discounted compassionate fares or at least will extend additional courtesies where passengers are travelling under such circumstances.

In this case, the original itinerary seems to have included appropriate MCT's (minimum connecting times). It is perfectly reasonable to consider a non-stop on a major ME carrier to theor base and a connecting flight to Athens (ex Australia) rather than a multi-stop through the Asian subcontinent - which could easily compound delays. The OP's complaint is based not on the fact that delays can occur, but how such issues are handled or resolved in-situ. And to have an airline suggest to you on the return sector that they can get you to SIN and that after that you're on your 'pat malone' certainly doesn't seem acceptable service to me.