And here is the letter I received from FINS, looks the reason is it will make commercial sense for them:
Dear Sir
I am writing to inform you that a management decision has been made to change your account to a ‘telephone trading’ only account. We believe that, given your style of trading and the volume of quote requests made by yourself during the day, that it would make commercial sense for us to offer you the same service over the telephone.
This change will take effect from Monday 13th January.
Stuart Lane
Director of Trading