St Courier — Irresponsible courier delivery & service

I am a reseller...I sent courier to my customer..but they didn't properly delivered...They hold the parcel in office around 4 to 5 days and askd custmr to get it on courier offc..Then why they collect the shipping charge for this?I called to head off & branch officeto arrange delvry to customer but they spoke very rudely and rigorously...I never had this kind of bad experience in any other courier office..Totally I am very upset & not satisfied with ST courier