Business email register

Dear Microsoft team, we are a Techpoint company, and our customers sent to us some defetive MS Tablets, which they are still within warranty.unfortunately , after updating your system, i cant reach you by phone like previous, and our email is not recognised by you.i need to repair customers devices ASAP.please register our account and provide us the steps how to open the RMa cases in Microsoft.im not able also to update the warranty according to the invoice of buy, you dont answer my request at all.i tried to do so from 2 emails:*** Die E-Mail-Adresse wurde aus Datenschutzgründen entfernt. ***@techpoint1111.deWaiting for your reply.