Hi HeleneF , and welcome to Flyertalk. First, I am sorry for your experience, though I would observe that as a frequent flier mis-connections happen sometimes. Of course how an airline responds is a sign of their quality - and unfortunately Qatar Airways does shine in the air but is not really well known for their on the ground service. I am presuming that you were in economy (Qatar does choose different hotels based on class of travel).

So, keeping it simple:

• As you traveled from Europe you are entitled to EU261 compensation: https://europa.eu/youreurope/citizen...nnectingflight . I am not claiming to be an expert, but I don't think you can get a refund part-way through your trip. However, unless there were extraordinary circumstances you are entitled to compensation, which should be a fairly substantial sum of money. Refunds are only applicable if you were denied boarding or the flight cancelled, or you decided to abandon your trip and return to your origin, not re-routed as in your case
• Whilst you didn't like the hotel, Qatar did do their duty of care by arranging a hotel for the day/night. Breakfast quality... a bit harder to measure
• The flight the "following day".. I am not sure if you mean departure or arrival: There are only 2 flights a day from Doha, so by missing the 2am flight (arriving 1pm), the next best flight would be a 8pm flight (arriving 7am). If that was already full then a 24 hour wait may have been needed
• For your hotels on arrival / people at the airport waiting - alas that is always going to be an issue if you miss your flights. In these cases your travel insurance should cover any losses there (and obviously the EU compensation will help too)

So, what should be your next steps, this is my view

1. Focus your efforts on "I want to claim EU261 compensation for a delayed arrival" - which should be 600EUR (distance of more than 3500km and delay of more than 3 hours). Unless they have extraordinary circumstances to claim, Qatar should be paying this (it may take a while How long does a EU261 claim take with QR?). I would be tempted to start this as an entirely new claim to drop the unnecessary noise about "I don't like the hotel" (see #3 below). I don't claim to be an expert, but I think your claim for a refund is incorrect, as you made it to your destination but with a delay - you could have claimed your refund if you abandoned your trip only.
2. Travel insurance claim the lost hotel / pick-ups and any related costs in Vietnam. If you don't have travel insurance, or they don't cover it, then in reality your EU compensation needs to cover. It is Vietnam, so they should (and Qatar give you a hotel). If this was booked as a package then you have more rights (but I presume not).
3. If you dislike the hotel, write a bad review on tripadvisor/google. Qatar gave you a hotel that they consider to be reasonable class. Based on my own experiences what they are giving you is what is considered suitable for international travellers - you don't know, but they may have had lots of disconnections so the numbers of hotels available was low. Particularly on the quality of the breakfast or location, that really isn't a QR problem. Try having the same experience in the US where there is not even an obligation to provide you with a hotel.... Putting this into your QR complaint just makes it hard to solve (counter argument - what do you want them to do, give you the 0EUR that the hotel cost you back as compensation?). Feel free to name and shame the hotel here as well if it is really bad (I personally think it is a mi-smet expectation)

You can use a claim company for #1 if you really feel Qatar is denying you and you've had enough, but they will take a chunk of your cash.