First year PhD without advisor, or experience, or a clue about research
Have a careful think: what makes you think that you will make a success of the PhD? I don't mean that in a harsh way, but as a genuine question. Your potential advisors seem to be recommending that you don't pursue the PhD, presumably based on their assessment of your performance over the first year. But perhaps you have abilities that they haven't really seen yet, or perhaps there were mitigating circumstances that led to poor performance, but you believe you will be able to turn it around. Once you have made this honest assessment, you can then make your case to your potential advisors to try and persuade them that you will be able to make a success of the PhD.

Of course, you also need to consider the possibility that these academics are right, and that you don't have what it takes to succeed in a PhD at this point in time. While it's not easy to face if this is something that you have set your heart on, they may have your best interests in mind. PhDs are hard, and are not for everyone. It might be the wrong thing to do to start off on a tough course, struggle through for a year or two more, and then discover that it really is not working out. Or you might stick it all the way, scrape through, but emerge exhausted and disillusioned. This may be what your potential advisors are trying to avoid, they have probably been through similar things in the past. I'm not saying they are right - they might not be. But equally, they might be. And perhaps your strengths are elsewhere, and they would be doing you a huge favour in directing you towards a more productive route.

You mention that you found it a big step up from your undergraduate studies, and that you lack research experience. Perhaps one option is to consider a research-based Masters course? This would provide you with something of an intermediate step, helping to clarify whether you are "cut out" for research, and giving you that vital experience. If successful, it would be a great way to provide clear evidence that you have some of the skills necessary for a PhD.

Again, please don't take any of this as a personal judgement. I don't know you, and I have no idea of your strengths and abilities. I just think it will be important for you to take a step back and make an honest appraisal rather than pressing forward with a single plan no matter what.