Building Inspector Job - Kommetjie, WC, 7976

The boundary wall between our house and our neighbours house is falling over. We are finding it very challenging dealing with our neighbour so are wondering how we can find out if the wall is on our property or theirs or if it is shared. It is 2.3m high and started leaning after the very strong gale force winds we had about a month ago. When we submitted a claim to our insurance company she blocked it from going forward claiming that it was their wall, not ours. Because of the challenges we would like to find out how we know who's wall it is, as if it is our wall we will have the foundations redug and the wall re-erected at a lower height. Please advise how we know who's wall it is. Thanks so much.