Measure to screen against multiple field values?

I have a fact table in a data model as shown below. 

I would like to screen the underlying records to identify the distinct clients (i.e. from the same Master Group and with the same Contact Name) who have at least one record of  Service Type = "Phone Consult" but no records of Service Type = "Live Meeting". 

In a pivot table (Master Group as rows), I would then want to display the names of the distinct clients 

(ServiceDetails[Contact Name]) who fit this criteria. I suppose this would be by concatenating any names with a comma separator. 

Can anyone advise how to solve for something like this? Many thanks!