Boundary wall

Hello , i have had built a boundary wall between myself and my next door neighbour, with a small fence on top . This was done at my cost and with full consent from my neighbour. However the neighbour has now sold his property ,and the new neighbours want to erect their own larger fence alongside the small fence,on top of the wall. Our president and Administrators have informed them that this large fence is against communidad rules , and this must not be built . However a couple of months down the line, our president has returned to the uk for a few weeks, and the larger fence has been erected. Does this wall belong to me , and can i remove their fence . thank you, Grace.