Cannot register my RBR50

Hi,

I bought a 2nd hand Orbi & when I try to register it I get a messages it is already registered.

I bought it from a lady in Witney, UK that had registered it to her work email address. She no longer works there & we can't get access to her account (do not even know if you can de-register a device).

Can someone please advise on how to get this registered to my account? 

Product Model: RBR50 Serial Number: 4S226B5A00676

 thanks!