Help.Problem with cats!!

Hi everyone,
I am looking for some advice for my mother about neighbours cats..It started someone gave him a few cats and now there are fourteen cats.They have attacked my mams cat and torn half her ear off and had to be brought to vet.there jumping the boundry wall and destroying my mams plants and pooing in her garden.
The neighbour was approached and he said he can have as many cats as he wants!!My mam rand the animal shelter and they sent someone out and he found that the cats were not neutered and the man from the ispca ( local dog warden I think) brought the four of the cats to local vet to be neutered and then brought them back to neighbour! They said they will be back in November for more of them to neuter ..Is this right ?How can you leave fourteen cats in a shed in neighbours yard.The warden said they are well looked after..No he does not look after them..There getting fed from other houses round the area.He does not look after them.My mam is nearly eighty and is at her wits end as to what to do.Why should she have to have her cat attacked and pay vet bills out of her pension..Any help would be appreciated please ..Also does anyone know anything that would stop them jumping wall and coming in to mams house? I told her chicken wire but she says she cant because its a boundry wall.Ive heard of vinegar sprayed on wall?My mam doesnt own the house its council but he owns his house.Anyone any advice?