s500 stalling on breaking
 

2007 s500
every now and then my car will go into a kind of limp mode and on breaking the car will stall i have recently had the cam magnets and cam seal replaced and an waiting for a seal to arrive for the offside gearbox pipe ( its leaking ) and a transmission fluid and filter change
the garage have said
ran short test and found the friction power of the torque converter lock up is to high and gearbox speed sensor faults carried out guided tests and found intermitent fault in gearbox valve body requires replacing with new valve body gearbox oil and filter change but mercedes have no valve bodys and dont know when thay will have one
anyone else have problems like this and any sugesstions on this problem
cheers