Cutting All Ties? - From Tired Mum

Hello Guys and Girls! I read the blog post about mollycoddled prisoners and would like to comment if I may.
My son is in prison at the moment and this isn't his first time inside either.
I have always stood by him like many other Mum's in this situation and I am guilty of running to his beck and call when he wants money or clothes etc.
Last week he rang me and asked for fifty pounds. He wanted me to send the money to an inmates girlfriend to which I replied to with a definite no! He hung up on me and that was that.
A few hours later (off a mobile phone) I got a call from a guy saying that my son owed him money for 'stuff' in prison. Little did I know and call me daft or whatever, that my lad was using drugs in prison.
I hung up on the mystery guy and then thought that if I didn't 'pay up' would my son be in danger? I guess he would be, but call me an awful Mother, I was not giving in to demands, in fact I couldn't and cannot give in to demands because I cannot afford too! My son rang me a few days later telling me that he is on another wing which I am thinking is some sort of protection wing? 
Not only do I have to put up with the shame of my son's wrong-doings and sweeping up the rubble when he goes to prison, but I also have to put up with crap whilst he's in prison too and I have had enough. I can barely make ends-meet myself and I work full time! 
I am just sat here in thought wondering how many other Mum's or Dad's are having the same issues with money demands from prison? Chris Crayling bans everything that benefits a prisoner/s yet cannot get on top of the drugs crisis in prisons? That's one battle he won't and cannot win! 
In the meantime and yes this is a rant, parents like me and probably many others are being badgered for money from our loved ones in prison. As sad as this may sound and I know this will not go down too well with some of your blog readers, but I feel like changing my phone number and cutting all ties with my son until actually gets out of prison never mind maintaining them! Maintaining ties with my son just labels me a human cash machine and I am tiring with it.