PayPal.
I want to pay for a race. PayPal is the only payment option. Try to log in, it's first time since I've been in China. They want to call or text me, but only have my old mobile number from the UK. There is no 'don't have access to this number' option. Just a dead-end. Unable to pay, can't do the race. It's happened to me before with them, had to set up a new account with a new email, but I'm not doing that every single time I want to use PayPal. Useless.