unreasonable complaints about tenants

Other

Please could you advise me on how to deal with a major issue. I have a tenant with a 3 year old in my flat the neighbours are (i think) unreasonablly complaining that she is letting her son bang his cot at night, makes to much noise and can hear cupboards opening and closing etc. I have rung the council who say they can do nothing, I am getting the neighbours ring me every few weeks saying they cant sleep if he wakes up. They have told the tenant and her mum that i should have known better than to rent to a single parent as they complained when i had a baby and when my first tenants move in. They have called her a prostitute, druggie (of which I have found no evidence) and said that she makes too much noise. Could someone please advise me?