Poor workmanship/unreliable worthless guarantee

I looked for people during November 2020 to do water proofing of my roof on the internet. Andre van Zyl's name came up amount others via the Kandua website. I received 3 quotes of which Andre was the most expensive. I decided to go with Andre due to the reviews on Kandua and my decision not to be penny wise and pound foolish. Initially everything went fine Andre came out worked on the roof and provided me with an eight year guarantee on workmanship and 10 years on manufacturers product. In short Andre has been back at least 3 times to honour his workmanship guarantee but no improvement in the leak of the roof in fact it seems to worsen every time it rains. Initially Andre responded to requests for coming back to remedy the situation. During our last discussion in February we requested our money back to find an alternative contractor to repair the roof. Andre has since ignored any messages/calls and even e-mails from Kandua.