Poor workman ship installing Head stone

I asked Avbob to manufacture and install a head stone for my wife. The head stone has been install on time, to me the workmanship is very poor. The one stone is very loose and I am very afraid when the wind will blow it off its stand. I did report this to Avbob to have it fixed. Till now nothing has been done. I am very disappointed with them I will not recommend them to anyone. The way I feel is to remove it and get some one else to re do. The only thing is it will be a 8000 rand loss and I think they should fix what they did .