Nightmare service and quality

I have placed a order with Iron-Steel (PTY) LTD ********** / ********** for a new double carport and garage door on . We got them through Snupit. On the 6th of December 2018 they gave us a quote and we accepted and paid the deposit of R14 300.00 they then confirmed to start the job on 12 December 2018, verbally completed by the 14th of December 2018. This did not happen, they come around in drips and drags and we paid them another R5 500.00 on the 18th of December 2018 when they initially started. Up to today the job is still not completed and workman ship is poor and the quality of material is poor. We would like them to remove the poor job and material of our property and refund us to the value of R19 800.00 as they are the worst company I have ever dealt with.