What do you mean "again, this failed"? Were the radial force variation readings unacceptable? Were they within the range that improvement could be made by reindexing the tire on the wheel? Was this done, or were they outside the range where reindexing will help? The 9700 measures both wheel runout and tire radial force variation and you should walk out with a data set that tells you if the wheel, tire, or both are acceptable or unacceptable.
If the vibration started with the new tires, then it's most likely that it is tire or wheel related.
Wheel bearings are easy to check for end play by "feel" and any competent tire shop should be able to check them. If they appear too be loose you should take it to a qualified MB tech for further inspection, diagnosis and, if necessary, repair.
BTW, MB wheels have a faint white "dot" on the rim flange. It can be hard to spot unless the wheel is clean and you inspect very carefully. The red dot on the tire should be indexed to the white dot on the wheel. This is called "match mounting" and indexes the highest radial force point of the tire (red dot) with the low spot on the wheel (white dot) and with a proper wheel balance will result in the least vibration.
If the tire shop does not understand match mounting, take your business elsewhere.