We're sending SMS messages to Contacts using the Send SMS Activity in a Journey Builder Interaction.
I'm quite underwhelmed with the integration between the contact model (in Contact Builder) and MobileConnect. For the uninitiated, you firstly need to create a Contact List in Mobile Connect, then create an Import Definition (still in MobileConnect) to import Contact information from a Data Extension to the corresponding Contact List (this process actually creates an Import Activity in the email app).
While this works, it appears that there is no solution for updating the mobile number. If the Contacts mobile number changes in your source Data Extension and you refresh the Import Definition (by including an 'Import Mobile Contacts' Activity in an Automation), then the mobile number is appended to the Contact in the corresponding Contact List, so the Contact now has two mobile numbers. Refer to screenshot below.
The SMS message is still sent to the previous mobile number for the Contact, not the new one.
I'm told that the only way to fix this is to call Marketing Cloud support and get them to reset the mobile number for the corresponding Contact Key — you can't edit the mobile number either manually or otherwise.
Does anyone know a solution to this?