Change use and serial number

Hi Teamviewers,

I'm having the issue that sometimes my channel is used by and ID unknown to me [ID removed by moderator] and I don't know who it is. Could you please "Kill" this id? Normally I would rase a ticket for this is but my serial number isn't accepted when I try to create a ticket, altough I copied and pasted this number from the last invoice for my premium subscrition valid to 10.4.2019!

Thanks in advanced.

Mid Ocean