Well... Your field may be different... In my old field we were told that if you don't get a fully funded scholarship (fees plus living stipend) to do a PhD in an institution that is ranked top 50 US-equivalent in your field... Then your field is telling you that your academic prospects in the field are pretty much zero.

People are probably staying a few years and then moving on, in part, because they don't have the money to pay more senior staff... It makes sense for people to... Move up in the world. It makes sense for the university to hire junior superstar graduates (the best graduates they can find) from the highest ranking institutions they can find... The graduates who might help bring up the reputation of the university by getting parts of their thesis (work they have already done) published... While they have your universities academic affiliation. If they go on to a higher ranking university then that is also good for your university insofar as they might (potentially) have distinguished alumni... Who might come back and give seminars on new research... It might be a good thing for current people at the uni to jump on their (successful) research bandwagon as much as possible...

I'm sorry if this is harsh... But it sounds like you aren't interested in research and they have been very clear with you that your work isn't up to the quality that is needed for a Masters thesis to get through your institution. Insofar as it is possible to get teaching work sometimes... You'll always be kicked around the bottom of the foodchain on short term contracts...

But you might tell me your field is hairdressing or something... That I know nothing about... That isn't 'traditionally academic' at all... So... I don't quite know what to say... I guess you could contact your supervisors again... The problem is that you sort of have a reputation for trying to get shoddy work through because you hate the work... And most people find this less than... Inspiring.