Welcome to the Magix user to user forums, so not a contact for any Magix staff and the software is not ours!
Since you purchased the software from Best Buy it is clearly the responsibility of Best Buy to supply the serial numbers that you need. Magix will have no record whatsoever of your purchase since you did not buy it direct from them so cannot supply you with those numbers.
I fully understand why you posted here but no-one here can help you, sorry.