Poor communication and after sales

Our geyser was leaking slightly, so they replaced it, but little did I know they replaced it with a lower pressure geyser. To make matters worse, they installed a lower pressure valve at the main water supply to the property without informing me either. So now the pressure to the other geyser at the back of the house is almost non existent. When I followed up, I basically got a response saying sorry this brand doesn’t do 100l ****pa geysers. And when asking why they didn’t use another brand they didn’t give a definitive answer. They also said a solution would be to move the main pressure valve closer to the new geyser but then it won’t be in regulation, shocking that they’d recommend that knowing it’s not right. After going back and forth they still haven’t owned up that not informing me was wrong. I would've stopped the install if I knew they were going to ruin the pressure to the rest of the property.