Sorry you're having trouble getting this battery to charge fully in a reasonable amount of time. Sometimes it proves beneficial to allow the battery to obtain a complete charge before using it the first time, then allowing it to drain completely prior to charging again. This may need to be done a couple of times to fully condition the battery and may resolve the charging issue you are having.
If you find this does not improve the performance, the problem may lie with either the phone or the charger. Do you have a second charger you can try? If so, does the phone charge just as slowly? This would dictate whether or not the problem is with the phone itself. Should these problems continue, please do not hesitate to contact us for any additional replacement options that may be available to you.