Regus threatening to take legal action if set amount was not paid.

[TalhaG]

I had paid one of the UKs biggest property rental company name Regus. I paid Regus around £500 in Jan 2024, to have a small space where I can sit and work quietly. Regus took my money and told me the space isn't physically available it was a mistake becasue Admin team didn't update online listings, so I would have to pay more to get an alternative space. I had refused to pay, and had correspondence with Regus back and forth till Feb 2024, but nothing was resolved nor Regus gave me my money back.
Instead, they started sending me monthly rental bills for the space which they said doesn't exist.
When I refused to pay the rent for non-existence magic space, they started sending me emails and calling me to pay the monthly rent or otherwise, so far according to Regus I happen to owe around or over £2000 to Regus for this magic space.

I have tried property court, Sheriff court in the city I live, Sheriff court of the city where I paid to rent the space, all the departments have turned me down with one or the other objection. I have documentary evidence of everything Regus did and are still doing but, no one can help or at least guide how to take a legal action against Regus, and who should I approach to ask for the money they have scammed me for the caused me immense distress the whole year.
Is there any way I can sue them? Because I don't know who to approach and what to do. Can anyone here help?

[PallasAthena]

Which city do you live in and which city is the Regus office space in?

[des8]

What is the full name & registered address of the company invoicing you.