Failure to adhere to guarantee conditionson geyser

On the 12th March 2016 this company visited my house in order to attend to my leaking geyser after realising that the guarantee on the geyser is still valid as it expires at the end of April 2016. The artisan looked at the pressure valve which is outside the house lying almost 5 metres away from the geyser and told me that the guarantee has automatically fallen off because the pressure valve is not recognised and manufactured by them.. According to them the pressure valve should be compliant to their systems. I asked to what extend does it affect the geyser since valve is too far from the geyser and where did they show this condition when one purchased the geyser. They could not give a convincing answer and their plumbers left on the spot. I called Mr Wits who apparently had already instructed them to leave and he was arrogantly telling me that he cannot unfortunately help me and must stop wasting his time. I made him aware that it is clear that his reluctance to replace the geyser is simply because its guarantee will expire at the end of next month and not the reason he cited. I then decided to purchase the new geyser. I am therefore claiming my reimbur*****t of my purchase money