“Despite the existence of a dispute of fact, the FTT decided to determine the application without a hearing. And despite the absence of positive evidence of service, and despite what Ms Barton said to the FTT at the case management hearing to the effect that she and other residents had not received service charge demands from the previous manager, the FTT found that the demands had been served. It is arguable that the FTT reached a conclusion on the basis of an unfair procedure, in that it did not conduct a hearing so that oral evidence could be tested, and it is arguable that the FTT reached a conclusion that was not open to it on the evidence before it.”