Focus rear wheel bearings?

I got a 2008 Ford Focus, an the situation is that I hav been heaving problems with the rear wheel bearing (noise). I repleced it for 2 times on last year, first the bearings presented factory defects (was generic brand) so the mechanic said a brand change was better, it were on last august, but nowaday I heard a little noise.

What can I do to fix it?

These bearings has no lubrication by myself.

Were they properly torqued to seat the races? Then, did you establish proper end play? Skipping these two steps will destroy new bearings.

Do not save money buying rubbish bearings. Buy genuine Ford bearings.
Get a Ford dealer to fit them properly.