We will need to know what the brand and type of heater this is and if you are referring to your domestic water or just the boiler pressure.
I'm not totally familiar with that unit but usually there are two screw adjustments and a looped piece of hose that are required to fill combination units. I will leave this question open for others to see also.
Would you say it's a braided hose ?
Is just hanging somewhere and not connected ?
yes you do not want to take them off, there should be set screws close to them on each side that when opened allows water to flow form the domestic side into the boiler which fills the system up, you may end up paying the price this time and just make sure you watch what they do to get water into the system it is usually a simple process but very difficult to explain without seeing what you have, is it possible for you to take some photos of that area so that I can identify for you how to do this ?
I fully understand the inconvenience of such an essential thing as warm water.
Hopefully he can get it going for you,
A flash camera might help.