We've lived in our flat for around 6 months. We have one upstairs neighbour with three children and a downstairs neighbour with 2 children. We have 2 children, DD age 4 (with autism and PDA if relevant) and a toddler.
We introduced ourselves to neighbours when we moved in and apologized for any noise on moving day with building furniture etc. Around a month after moving in, the husband told us our toddlers walker was really noisy for them and upset their child with the noise so we apologized and got rid of his walker even though he loved it.
They regularly bang on our ceiling whenever the kids are playing. They bring it up every time they see us. We never play music, keep the TV at a reasonable volume, kids go to bed at a normal hour but they do run around in the day and evening and our toddler does push/pull things over occasionally as toddlers do. I regularly tell DD to stop running but she just doesn't listen, not sure if this is due to her PDA or just being 4. DD will often have meltdowns where she's hammering the floor too which I appreciate must be horrible to listen to and we do pick her up or move her to our bedroom when that happens. We bought thick play mats for the living room and their bedroom to try and reduce the noise.
They've just hammered on our floor again so I've text apologizing if DD was too loud when she was playing with my DH (she was jumping on him) and they've responded saying it's really bad and all they ever hear is running and banging and dropping things all day long and that she doesn't let her children run around at home. (I think they're around 5 and 11)
I'm not sure what to do. I don't want to cause a bad relationship with them, our upstairs neighbour we can hear everything too so I appreciate how horrible it must be. I'm not sure what else to do and i am sympathetic, do I need to ban the children from any kind of running/jumping in their own home? What else can I do?