My geyser was downgraded to a 200LT

My Kwikot 250lt original geyser was supposed to be repaired but it was downgraded to a W.E Geyser 200LT. The Contractor Geyserman insisted and misled intentionally that it will save a lot of electricity and that the hot water will be sufficient. We complained after the installation. Same Day Plumbing came to set the temperature to 70 degrees. The geyser seized the thermostat and the element. The new contractor Handy Aid is refusing to set the geyser to 70 degree again stating that it is not recommended by the manufacture contradicting the last contractor. First Property Acceptance failed to intervene and send me all the reports or processes I requested.