Singer disgusting service

On 10 June I purchased a singer 4423 from stitch and go in Durban. Within a month of purchase the machine stopped working while sewing a cotton flat sheet. I contacted Amanda who collected the machine who responded that I had damaged the machine and without my consent went ahead with the repairs. I have since contacted head office on 30 July and 5 august. Lorien from head office advised that the machine is under warranty and will get Amanda to contact me. To date I have not received any communication from either with regards to my machine. Yet Amanda has been emailing me with the invoice for payment. I'm am digested with the service I have received from Singer. They have no respect for the client when promising to respond to my queries