What do you do as Support when you know you can't carry your adc, and jungle completely ignores bot?

Played a game earlier, I was Leona, my ADC was Ashe. We were up against a Trist/Karma. They were going all in Ashe early, so I e'd to Trist to root her, stunned her and almost had her dead (but I was almost dead and so was ashe). Ashe flashes in and misses Trist with her spreadshot, at point blank range. So at that point, I knew we were in trouble. I ask for help from our jungle gragas, saying we've got an aggressive lane and need help. No help comes. Ashe keeps getting out of position, and I try to peel the best I can, but she keeps feeding. Again I plead for help from our jungle, no help comes. At this point shes 3 0 3. I've only died to her once, because I'm trying to play safe while still protecting the feeding ashe, but it goes further downhill and I start dying. By this point our tower is almost gone this time I literally BEG for help from jg, he still ignores us. One more push with help from their fed cho'gath, and down goes 2 of our towers still no help. At this point I try to roam to support our fed lucian, but he wasn't paying attention and tries 1v1 the fed as hell tristana and gets hammered, and it goes WAAAAAAAAY downhill from there. My question is what should I have done?

I asked for help multiple times until it became begging, and I couldn't very well say Ashe sucks I really need some help down here or i'd be toxic, and I don't want to be. I just don't know how I could have helped my team win that one. When did team up with lucian against those that weren't fed as hell we did great, but once trist or cho showed up, we were doomed.