Hi and welcome.
I think that I would get your money back as you can purchase a new board with three years warranty for not a lot more. Even this exact motherboard is available for just over £80+VAT brand new:
http://www.transparent-uk.com/gigabyte-ga-z77x-d3h-motherboard.htmlThe thing is I wouldn't be particualrly worried about the CPU fan header as you can always use one of the other headers or even power the CPU fan directly from the PSU so that isn't a big problem.
What would concern me more is what else does the track connect to. If it is only the CPU header then fine but I suspect that it also connects to the memory or other components. This has had an awful lot of power drawn through this track to have burnt it like that.
I think £46 is a lot to pay for a burnt board to be honest.