Drove it back to Mercedes for them to have another go at the brake booster recall.
....
Does your Merc have electric power steering?
I ask because I got a recall letter from MB saying that they need to look at 3 bolts between the motor & the rack .... something about rust.
I 'm reluctant to take it due to the 'recall' re their emissions software update. The web is full of tales re the update & NOX sensors then failing, and owners taking their car in for other work to then find out that MB have done the update without their knowledge or permission.
There's also another recall re water ingress into the spare wheel well ....
It doesn't as it goes. No Dpf/Adblue or NOx sensors either. Which is nice.

Your ML may be new enough to have escaped the booster recall

Easy enough to check viable the DVLA MoT history checker

Taking of NOx sensors there's a chap here who has bought his C Class in for an intermittent EML. Apparantly it's the NOx sensor. Interestingly, it is a 2016 car so would have had the recall for it in 2017. Fortunately he has the extended warranty so it's covers (whenif it comes off backorder

) the sensor and any breakdown in the meantime... Probably.