InvestSolar Inverter trolley - supply incorrect units

I have ordered and purchased a 3kw Inverter trolley from Invest Solar, however was supp**** with a 2,4 kw instead. Phoned Ernest who sold me the unit and he claims I am looking for trouble. Consumer protection act does not allow this. Please correct urgently. Ernest also changed the paperwork now to match a 2,4 kw, although the quote clearly stated 3 kw.