LMAO. In 1975.
Meanwhile, in the real world, a 3rd is basically useless to someone starting a career in the 21st century.
OP I know you won't like to hear it but a friend of mine got a third, she didn't understand how it happened, but the rest of our friendship group all did. It wasn't that she didn't study, it was that she just couldn't actually do the critical analysis expected of our subject and she genuinely believed she was on the same level as the rest of us.
Every single essay since the beginning of first year had given us an A4 sheet of feedback detailing exactly what was wrong with our work. We had to be proactive and book appointments with tutors for the various modules to get help but those of us who went and got the face-to-face feedback were able to work on our issues and those who spent hours in the library "researching" from 1-2 key texts then wrote their entire essays based on those didn't do very well.
Degrees aren't classified based on final exams, they're the culmination of marks across at least two years of modules and an extended research project with regular supervision meetings. Getting a third is only a surprise to people who refuse to take feedback on board or accept criticism. Often the same people who say they had a lot of "bad tutors" or that they were "misunderstood".
A similar thing happened to a girl who failed on my MSc for similar reasons (she did her undergrad at an ex-poly and couldn't cope with the quality of work expected at a RG uni) and she complained and got nowhere because the uni had given her countless feedback, offered one-to-one support and resubmission opportunities to improve.
Please don't suggest further study to her, don't let her get more into debt for something she's so very unsuited to. Let her call it quits here and find another path for her own sanity and bank balance. She'd be much better off getting on with a career that doesn't need a degree and spending the coming years getting ahead in that than throwing bad money after good on further study.