How to contact after-sales service

It’s been more than 2 weeks since I made a return request with the after-sales service and no response. How can I contact you effectively ?

We are sorry. We had several holidays so its been delayed. I checked and you wanted to return H8.
You can do it but you would need to pay the shipping cost .If you agree i will tell my colleague to send you the instructions.
Right now we dont have H7, is possible that in 1 or 2 weeks arrive again to the German warehouse.

if you guarantee to send me a h7 when your stock from Germany
yes send me the instructions for the return I will wait for the exchange

Thanks a lot

I told my colleague to answer your mails.