Late rental payment & property management company unresponsive

[Lauren M.]

I closed on a duplex at the end of November. I kept the management company the previous owner used. One of the tenants only paid half of a month's rent for December. I brought this to the property management company's attention last week and they said they would follow up with the tenant. I haven't heard anything since then and I've been trying to get a hold of the management company by phone and email since Wednesday of last week and haven't heard anything. 

How should I handle this situation? The tenant has clearly broken their contractual obligation by only paying half of the rent. The due date is the first of the month and it's the twelfth of the month as I write this. I want to serve notice that the tenant has three days to make their payment before the eviction process is started, but can I do this without the management company knowing? What if the management company hasn't entered the check into my online account, but the tenant has paid since last week? I am assuming the tenant is testing the waters now that the duplex is under new ownership though...