Similar thing happened to me and I rectified it by changing the DAB aerial and base. I have sat nav so the replacement part was a bit pricey for what it was. It's a reasonably straightforward enough diy repair though. You can access the fixing bolt and connectors by prising down the tail gate end of the headliner. To do this, first remove the side pillar trims, then release the trim clips holding the rear of the headlining which allows it to drop down sufficiently for full access to the mount.