Normally they are very good in replying, certainly within a day or so.
That said, I do know that they are very busy at the moment which might be causing some delay in replying as the direct to sales seems to be really taking off and Ecowitt is starting to become well known.
Drop a note again.
The best e-mail to use is support@ecowitt.com which should get a response from Lucy.
There is also a Facebook page which you could use as a contact mechanism.
Be aware that Chinese New Year (Spring Festival) will be approaching on 25th Jan and that will definitely lead to some delays.
They normally shutdown for a couple of weeks over this period.