Serial number is already activted

Hi

I bought a second hand Komplete Kontrol A25. The seller said that he did not activate the serial number, but Native Access shows that it is already activated ... Naturally, the seller and I cannot transfer the license to my account. I have a serial number on the device and the same one on licens card. And I have purchase receipt from seller. Technical support is not responding, I wrote to them 2 times already. What can I do?