Yeah, I hear you. Did you make sure to turn off user pages in the Sitemap settings? So you're not telling Google to look at them.
The only other way to prevent Google from crawling them would b
1. Robots.txt blocking /members/ -- but then Google will complain that they are robots blocked
2. No-Follow all links to /members/ -- controversial choice. But would presumably hint to google not to follow. Google will prob still complain.
I do think Google eventually "gives up" on the 403 pages, so should be a relatively small amount of your crawl budget. You can grep your server logs to see how much time Google is actually spending on your /members/ pages. it might make you feel better.