Management Company not revealing its address or registration number

I own a leasehold flat and the management company are demanding an extortionate service charge. I have referred this to the Residential Property Tribunal Service for them to decide what a fair level of service charge would be.

My specific question relates to the management company itself though. None of the letters I have received from them show their company registration number or registered address. The only address they have provided is a PO Box number. I have written to them asking that this detail be provided and received the reply that they are not prepared to get involved in needless discussions and that they would commence repossession proceedings if I did not pay their charge.

Their company name actually appears wrongly on the first demand I received from them, something I only became aware of after receiving subsequent mailings from them. Also they have not provided any explanation or breakdown of how they arrive at that particular level of service charge, only a blunt demand.

They informed me in one of the letters I received from them that I had covenanted by my lease to pay this level of service charge. This appears not to be the case as I can find no mention of it in the lease.

Can this company legally demand money from me without providing their company number and registered address? Also should I take any action regarding the misleading statement about the terms of the lease?

Any advice gratefully received.

Thanks