Petition Station kiosk facing ruin

I have been working at my kiosk at Hampstead Heath station for 5 years. My lease has expired and London Overground is looking for a new operator who will pay far higher rent price, double the price I have been paying for years. I have invested all my money at this kiosk as I thought I would be working here for many to come. I spent money on the infrastructure of the station; from pipe and electricity work leading to the kiosk, I have always paid my rent on time, I have not received ONE single complaint from station staff or passengers during the years I have been working here. I have tried everything with the London Overground. I have tried to talk to them, to persuade them but no one wants to talk to me, my calls ignored and my letters also.

Please help, I am a father of two and this job is all I got, I don’t know where to go, I don’t want to be unemployed, I just want to work, provide for my family. I have done nothing wrong to deserve this.
Thank you