I am not a professional in this field, but I had to deal with similar repair stuff in my house. I had to buy some new wall plugs, but I had no idea where I could buy some. Luckily, one of my friends worked at https://www.scrooz.com.au/screws/plasterboard-bugle-fibre-cement-screws/ and recommended buying some plugs there. Also, I was able to buy some new screws for my house at a reasonable price. If you are interested, check it out on the internet for more information. I am sure you will find something.