I'm sorry about your friend Wrongsideofhistorymy arse (love the username!) When people are in the grip of addiction, there's really nothing others can do to help unless the addict's at the point where they will accept help. Those moments of clarity are pretty rare, sadly.
I have briefly come across Gabor Mate (on a Russel Brand show I think) Veevee, will look in more depth, having an addictive personality never goes away, all I can do is funnel it into thing that won't harm me - ie I stay away from romantic relationships and do a fair bit of exercise. Thank you, and a pat to you MissConduct, I'm glad you managed to escape the crapness of addiction too.
Heroin and (crack) cocaine can often go hand in hand lawandgin, heroin makes cocaine/crack comedowns easier to deal with. Cocaine's a horrible drug all by itself though.
I was able to access drug services easily enough Dane, (many years ago, mind!) which consists of providing drug tests and prescribed methadone or subutex. My MH was pretty dire following my detox, as I'd been using the drug to keep all my anxieties at bay, and of course they all thundered back into my life. You do very little thinking and processing when you're an addict, so stay stuck at an age much younger than you are - I've probably done most of my "growing up" this last year. I know I'm always banging on about it, but I think if drug services and MH were more synergistic it would help, less people falling through the cracks.
It's not so easy getting a place in rehab - you usually have to break the law first then the probation services pay for it, which results in many people being in rehab who don't want to be there but prefer it to prison. When I was sent to rehab I wasn't ready, as far as I was concerned the drug was my reliable friend and it made no sense to stop. Long-term addicts who have been unable to detox within the community will sometimes get funding from the LA for rehab.