I have heard that the use of R404A for servicing is banned from 2020, is this true?

Yes the new F Gas Legislation that came into force on 1st January 2015 prohibits the service and maintenance of stationary refrigeration systems with virgin refrigerant with a GWP equal to or greater than 2500, for systems where the charge is greater than 40T CO2 equivalent (10.2kg of R-404A).