Poor Service by Aquacolt - plumbers

In January 2020 I paid Jason Coltman of Aquacolt R 300.00 to install a new toilet seat. I have repeatedly left messages for Mr Coltan to contact me as the toilet seat is faulty, the brackets holding the seat to the toilet keep slipping out and the seat keeps sliding off the toilet. To date I have had no response to my phone calls, I would like the seat to be replaced or get a refund of my money. Regards Barbara Craucamp