Sidlops

We quite regularly get paramotors passing over East Leeds, they're quite nice to see, and I definitely get the appeal. This afternoon I heard one so had a look out of the window and saw one very low, so thought I'd go upstairs and grab my zoom lens, see if I could catch any cool shots, as I have got some nice ones in the past and this one was closer than normal. As I watched it flew over our estate and started circling the local park. From this window I'm looking downhill over the roofs of houses. They then seemed to lose control, or be trying to show on off, and spiralled downwards rapidly swinging like a pendulum with the canopy being lower than the pilot a few times. They levelled off much lower, then carried on circling and got lower still. They must have been under 100m at this point, possibly as low as 50m as they eventually went below the houses and trees. I wondered if they were trying to land in the park, but they powered up and flew back up to the same sort of height I normally see them. Then they dropped and circled below view again. This repeated a couple more times and then they flew off south east out of sight. I'm concerned that one pilots poor choices are going to lead to an accident or repercussions that affect the good ones out there. There's no visible markings to identify, and I've no idea where they would be flying from but I guess it's not far from the city. I'm hoping someone here might be able to either advise on a way to contact someone to report it, or be able to speak to someone directly about their behaviour. I may be wrong, but 1500ft over a built up area is what I've read to be minimum, and swinging like a pendulum with the canopy wing lower than the pilot seems dangerous even if intentional.