Coating peels off, and claims of a guarantee are false

Neil Cloete of Spectrum Consulting quoted to put a waterproof coating on our Cemcrete patio. He claimed that it came with a 5 year guarantee. However the epoxy was 50% peeled off after 6 months, and had a terrible yellow blotchy appearance. When asked about the guarantee, he gaslighted, implying I'd somehow invalidated it in subsequent discussions. In his own words:

There will not be any refunds for this project. Both Dan and myself made it very clear that the process used was not the recommended method. In particular, I pointed out at the outset that the leakage was due to the failure of the waterproofing under the Colour Hardener and that everything had to be removed back to the slab for a satisfactory repair result. However, you chose to go with a surface coating as you wanted to retain the Colour Hardener appearance.