Appalling service from Bosman Plumbing (Constantia, Cape Town)

Bosman Plumbing (Plumbing & Renovation Services) in Constantia, Cape Town, South Africa gave me APPALLING SERVICE. Outsurance required that I use them to replace the element in my geyser. Firstly, Bosman refused to replace the element without also replacing the thermostat even though I had a new thermostat installed a week before Bosman was called in and I informed them about that. Secondly, Bosman did not ***** in a device properly after installation, causing the passage below the geyser to be flooded. I had to wait an entire day before they sent someone to fix the problem that their employee had created. Outsurance undertook to pay for the extra hours billed. Yet, I received a bill from Bosman for extra hours and the replacement of the thermostat (in addition to the element). The work was done less than a month ago; they invoiced me just over a week ago, yet they've been harassing me for payment.