I've had issues with corrosion in the past and managed to rebolt the point at which it detached but it has now happened at a second point with little to reattach.

Any way of sticking/repairing to get it attached again without replacing it?

It's currently laying on the exhaust. As its the one between exhaust and fuel tank I'm pretty sure removing it or at least the loose part is probably not a good idea?

Do you mean the hole around the fixing is too wide to refit?  If so, you can use a large flat washer.  Or even drill a small hole through a larger flat piece of metal to do the same job if the hole is bigger than a washer.

Missing heatshields are now an MOT fail, though whether your tester will actually fail it is another matter.

Hi There, Try using Aluminium drinks can, Using good pair of scissors cut around 1 cm to 2 cm from base of can. So you have small cup container left then fold over walls to centre may have to cut, Then flatten down with hammer so you have a squashed disc. Punch hole through centre size for stud bolt and place over rotted heatshield hole then add nut. Or if you want go to car breakers yard and get any heatshield available. And cut up to make large heatshield washers.

                             Hope that helps Henry