hi,
1/ you need to increase the CE License for this site.
2/ or/and you need to decrease CE usage (by activating specific feature, or by reducing number of HSDPA/HSUPA users)
3/ you need to better balance the load between cells / carriers. Are all cells or carriers using the same CE pool ? Try to find the cells attached to a CE pool which is less used, and push your traffic over there.
Regards
pix