Find a professional hot water system contractor in Keysborough

My hot water system (I think thermostat but could be wrong) is not functioning properly. The temperature fluctuates similar to the water being used in two different rooms when it’s only being used in one. Quotes for fixing the issue, please let me know how much the parts cost separately. Please disregard the budget, I’m just looking for honest quotes.

Hot water from solar running out so quickly in cold weather.

Leakage from the small hose connected to the hot water unit.

Our hot water in the shower can go completely cold after a few minutes, even twice in the same shower, and then works fine after you turn it off, wait a little while and turn it back on. Temperature's also unstable even when the water is warm. The service technician insists there's nothing wrong with the system and it's because the combination of flow and temperature we are using the shower at would just do that, all we need to do is use the max flow and higher temperature but I find that ridiculous as that won't be too hot for us. So I want someone else to have a look and see if there's any other problem with it. - Due date: Flexible

My hot water system in the bathrooms are not working properly. It's not hot enough. When I turn it on maximum temperature. - Due date: Needs to be done on Wednesday, 23 August 2023

Removal of current hot water tank (solar, approx 10 years old). Supply and install a new tank, we’re looking at the Aquamax 390 but open to suggestions. - Due date: Flexible

change hot water system; my existing one is 30+ years old. and it stays on the roof. i have been told it runs on electricity. change to a new one.. heat pump may be.. open for suggestions. we can talk out the deal in person. - Due date: Flexible

Hot water is not hot for some bathroom and also pressure is less - Due date: Flexible

The leaking is pictured in the photo