By far my biggest source of drugs have been found while waiting in line for my dose

Regularly offered benzos or to buy/sell spare doses of methadone and suboxone. People meeting there to go and get some dope after their m-done, off their heads on ice etc. Got to be one of the most non-therapeutic environments I can think of apart from prison.
Last Christmas while grabbing my take aways a group of creepy looking dudes starting hassling me for some. Said 'No, sorry mate don't have enough' - 'aw common bruv, I'll fuck you rotten - 'nuh sorry mate' - (different guy in super creepy voice) 'he wasnt farrrkkkinnn asskkin bruv' (very crazy look in his eyes) - I smiled because I thought they must have been joking but they gave me the dead eyed stare - they followed me as I was walking off and luckily this other big samoan dude who I'd known for years came around the corner to get his dose and told them to back off. Apparently one of them had just come out of prison for rape and burglary. Needless to say I only go to my chemist at busy times of day now...
Don't get me wrong there's awesome people who are on the program...90% of them are harmless and friendly if you strike up a conversation, even the people who have spent time in prison are usually decent. It's not helpful to put all these people together in the one spot every morning though...because not everyone is on the same page in wanting to work on their recovery. I've seen people who've been estranged for years meet again at the chemist and fall right back into old patterns when they get back in with their drug using buddies.