The HHT hasn't been produced or available for over 4 years!!
Dealers use IBM laptops with a program called Star Diagnosis. Available from Mercedes for a MERE $20,000. That includes a license for 1 year.

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MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator