guys i could really do with some help im really stuck.

in febuary my ford ka 04 plate overheated (light) i found it to have no water in collant bottle re-filled emptied again within days garage found i had a cracked theromstat housing replaced at £150 fitted.

roughly 2 weeks later overheating light returned and it was boiling when i checked water its mixed with coolant of course but it was now not losing water.

garage did a radiator flush and replaced water/coolant garage said radiator did seem to be better hose hot top and bottom they also said water pump looked to be working fine and the fan was working as it should(kicking in).

car was then fine for a week or so i do only small journeys 10-15 miles a day then 10 mins in to my journey light returned car had been sitting for 2 days.

the car is not losing water/coolant the heating inside the car works perfectly i have checked oil cap it looks very clean.

im terrible with cars and this has a lot of people stumped only other thing someone mentioned was a fan switch but could it be that if the fan is kicking in???
please help.