Ok, i've done some more research. TIPS document GI82.62-P-059101 (which has strangely disappeared from the index) says this problem occurs on 204 saloon/coupe, 207 coupe, 218 coupe (218.3) and 212 saloon and is caused by the comms nodule (for live traffic) irradiating interference into the antenna amplifier. Disconnecting fuse for comms module fixes the issue thus proving this. A new antenna amp is being created TIPS document GI82.62-P-058307 is a document for 212 and 218 and sound system, and says that the comms module can interfer with the sound amp and cause that GSM noise that we are all familiar with. The fix for this is to relocate the antenna - on W212 in the middle of the rear shelf, and on 218 on the left of load compartment. My suspicion is that relocating the antenna on the 212 and the 218 will move it away from the antenna amplifier (and the DAB tuner which is near the sound amplifier) and may well help. So, anyone with a W212/W218 with this problem and with Harmon Kardon could point out tips document GI82.62-P-058307 to their dealer and say 'please do this under warranty and see if this fixes the DAB issue also" I'd love to know if anyone does this and it helps Richard