Frustrated with my once-close friend
So my friend has mental issues (paranoia, etc) and so does his girlfriend. I've known my friend since school and we've often met up on a weekly basis. However, in the last 6 months or so he's become extremely unreliable and frustrating. To cut to the chase, he changes his phone number each week typically. He'll send a text saying it's his new number, ask if I want to meet on a certain day, then follow up checking if I want to meet on that day. That day comes and either the phone is dead, off or he has an excuse as why not to meet. He's been doing this every week now for months. He has on occasion asked for £10-20 (drugs??). Like today I told texted to tell him to get in touch when he can be more reliable, he said sorry he missed my call, later followed by "I need to go to the hospital can you lend me £20?) - ZZZzzz. (I've eventually always had back what I've given him but it considering his behavior I won't be doing anything for him anymore.
What should I do to stop this, it's quite ridiculous. Is it been done on purpose, I mean to do this every time now is quite crazy and once I got a text from his girlfriend saying "He doesn't want to meet today" Even though he'd arranged it.
He has said that his girlfriend is doing it behind his back without him knowing, I don't have any direct access to my friend as it all goes through her. If I ask her to get him to call me back, he never does. If I call, she answers. Amazingly, he's usually not there, or isn't available to talk. He ended up in hospital, he claimed she was trying to cause trouble. But I don't know.
What do you think I should do to stop the stupid cycle. I simply want to meet now and again, not have this stupidity each week.