LONDON—For people with family members trying to get out of Afghanistan, recent days have brought a frantic mix of fear and frustration. In west London, many relatives are doing what they can: seeking advice and information from the Afghanistan & Central Asian Association. The organization was set up to support refugees 20 years ago, the same year a U.S.-led international force drove the Taliban from power after the 9/11 attacks. Shah Hamdam, a 52-year-old who arrived in the UK in 1998 via Pakistan after fleeing Afghanistan when the Taliban were in control of the country, said he would do anything to get his sister, a television journalist, out of Kabul. “She is begging,” Hamdam said. “She says, ‘Find a solution, find a way for me to get out of this situation at the moment.’ I try, I try, I knock every door to find a way to bring her over …