Just for Information I Contacted BMW customer services regarding this problem and asked if it is a known issue.
Heather from BMW....
We collate failure reports, customer feedback and part order details, which are a more reliable source of information, to determine if an issue is common. We monitor the performance of all components used in our range and where there is an established trend of failure in any of these, we take the appropriate action. I can confirm that the issue that you refer to has not been highlighted as being inherent with this accessory.