What to do when team/ally feeds your lane enemy?

Recently I played a game where I laned against an Ekko top, and all was going well for a while. I was Annie, so of course he was rushing a spirit visage to better trade with me, but I played safe, got the cs I could, and only took trades I knew I would win. All is good, but then level 6 comes and he immediately runs down toward mid through river, rather blatantly as well.

So of course, if he was planning to bait me I would lose the duel and potentially die. So I call my MIAs instead. I quickly noticed Jhin down at mid lane was auto attacking the turret with half his health gone. So I scroll down to mid lane and issue the "fall back" pings, to which he does not respond to at all. He continues to attack the turret and of course, dies because of it.

This went on...I believe in the laning stage alone, Jhin died three times to Ekko due to lack of acknowledging the pings I sent him. It felt like he was just dying over and over, and soon he kills our adc, support, and jungler. Unfortunately I was unable to roam myself, as they'd sent Volibear to apply lane pressure while he was gone. So I either had to give up a tower and risk my life to help my underfed team, or leave them to die and farm. I decided it wasn't worth the risk, and I farmed so I could be helpful later and not feed the enemy myself.

So Ekko comes back into lane with his 6 kills and I cant poke him at all. I do no damage, the other lanes begin losing, and I feel like even with all my farm I'm unable to help my team at all. So when Ekko left lane again, I rushed the turret, destroyed it, and teleported mid to try and help them out, but at this point all we had was a single turret at half health. I got a kill off Ahri, but that's about the extent of my usefulness to the team. We surrendered, and Jhin complained that I didn't help the team and I just spent the whole time farming.

So what do you ACTUALLY do when this happens? Do you give up a turret? Do you farm and hope for the best? Or is there some alternate route I haven't considered? Also if I am in the wrong here, please tell me. I didn't make this as a rant, I just felt so hopeless and useless in this match that I wasn't sure what to do. Any advice would be helpful, cheers all.