In muddy and wet conditions, Eibar took advantage of Girona's failure to adapt to the pitch at Ipurua as the Basque side won 3-0.
Eibar showed a far higher level of intensity and, playing at home, were more familiar to the conditions.
Ruben Pena gave Jose Luis Mendilibar's side a 1-0 lead in the 37th minute after Fabian Orellana fed the 27-year-old to powerfully fire past Bono from the right-hand side of the box.
Just after the resumption of the second half, Charles doubled the home side's advance with a sumptuous chip over Bono in the Girona goal.
The result was sealed 11 minutes later, in the 57th minute, as Eibar were awarded a penalty after a foul on Sergi Enrich.
Charles stepped up to secure his second goal of the game, sending Bono the wrong way.
Eibar climb up to 10th, while Girona remain perilously close to the drop zone, just one point and two places above Rayo Vallecano in 18th.