Leasehold notice

Other

Hi,
I have an interesting problem that hopefully you may be able to advice on.
I purchased a one bedroom apartment in January 2009. I recently recieved an inpolite letter from the freeholder claiming he had not been notified of the purchase and therefore could not except ground rent, which has now become overdue. (without my knowledge.)until notice fees had been paid.
My solicitors had paid the management company the required fees, requested by them at the time. However they now claim that the landlord has removed their authority to collect notice and ground rent from them. We are now in the process of obtaining a refund from TMS. My question is this, at £500 the notice fees are high, but the landlord is now requesting nearly £600 for this service.
Have I any recourse to challenge these costs? it seems a blue print to make money to me.
Regards
Vincent