Does the fan work, has it got water in it??
Check these things 1st as you can do these yourself, the fan should come on around the 3rd bar aon the temp gauge or if it has a low temp stat around the 2nd (halfway) .
If it's loosing water then check hoses & see if you have mayo type stuff under the oil cap, mayo = headgasket if you're loosing water & can't find a leak.