I messaged their WeChat service account because I was curious to see if anyone would reply. The answer is "no", which didn't really surprise me because manning service accounts typically requires using a computer interface (i.e. same issue as email). When I stay at hotels I plan on returning to, I ask the front desk person about WeChat and he/she will give me a quasi-personal account that staff members share with each other (i.e. it's on a phone that remains at the front desk).

In any event, this particular hotel lists the same phone number on its Wx account and website, so I think that's the best way to reach them for now:
86-21-68618888