Premades in Draft Pick

How do you deal with premades in Draft Pick?

Let me tell you my situation. I solo queued in draft as Bot primary and Top secondary option. The queue popped and I was assigned bot and met with the supp guy begging me to go supp instead and the others saying "we're a 4 person premade".

The game has assigned me bot and I think I'm right to play as the position I was assigned. If I was assigned support I wouldn't be there begging to change to adc, I'd just have to deal with it. I told them that I'm not very experienced as support so wouldn't be able to but otherwise I'm happy to play along with their strategy. Fortunately this group was sorta ok about it and not a toxic premade but I'm not sure whether I'm supposed to change or what.

In the game, the support picked Zyra and I had a bit of a problem with his playstyle. I don't know how Zyra supports play out but he was a lot more like a second adc than a support. He was farming creeps and blocking my own cs, took multiple killing blows, wasn't warding. In the end we won, they were clearly a good team but I found it a bit annoying that instead of just going support as he was assigned he insisted on playing more like the adc.

Anyway what's the correct way to deal with this? I always thought premades should just go in blind pick. Secondly, a 4 person premade seems a bit like a cowardly way of avoiding playing support and forcing it on the 5th player instead. If they were a really toxic group I've no doubt they would have done that. Am I wrong? Should I just fold and do what the premades tell me or go by the role I was assigned?