Either...
Unclip it and take it to a hardware store and buy something similar to this picture...
https://www.northerntool.com/images/product/images/257342_lg.jpg
Or... Dont bother messing around - just reposition the remaining clip to be in the centre of your slim flourescent fitting - like the fulcrum of a seesaw - then any dangle down will be minimal.
Or... Just screw a short length of soft wire across one end of the fitting to support it.
The fitting is unlikely to be magnetic
By the way... Google searches for your INT 2826 show them being sold for silly money (£30 or so) - last year I bought similar downlighters from a specialist lighting supplier (Koltrane) for about £9 each.
Good luck...
Peccavi
September 2009