Your post doesn't contain enough information for me to respond constructively with what you should do. Only about what you need to consider when you're thinking "this support sucks"
It's not as simple as "they died 5 times" specifically when it's the support. There are many factors in why they did and sometimes NEEDED to die.
Things to consider when this is happening: Did you die a bunch too? Did the support die trying to peel/save your ass? Or were they legitimitly stupid and just didn't play safe for no reason?
I main support, and I will gladly die if it means my adc gets to live and continue to farm. I've done it countless times. Sometimes a get a stupid adc that tells me I shouldn't die so much. Sometimes I will get adcs that don't take advantage of my peeling to allow them to escape. For example The matchup is severely unfavourable, and while I'm peeling my adc just continues to try and fight. What happens? We both die. Instead of me leaving them to die, or saving them and dieing in their place, they make it the worst case scenario and stick around only to die right after they finish myself off.
In short, them "feeding the adc" isn't always the wrong thing to do. It's never a good thing, but sometimes it's the best thing to do if they're playing right and you are the one making the mistakes.
In general, though, CS better than your opponent, lane safely, harass correctly, know the difference between your support sucking and when they die purposely because it's the best possible scenario, and learn to recognize when your support is dieing FOR you.