I have been treated like a ******** when it is their staff that committed the ******** acts

I have used this company for the best part of 8 years for all my courier needs, however lately the way I have been treated is shocking. Firstly one of their staff members "helped themselves" to R1800 worth of my stock. The matter was resolved and my stock magically found, after a week of wasted work and me having to make duplicate stock - the cost closing in at about R3000 in LOSSES thanks to them. Since then the customer service has been shocking. They have been conveniently not seeing my requests and payments for parcels to be collected (often saying it just didn't arrive or must have gotten "lost" in the system), until a day or more later when I have to phone them and follow up. Their staff are rude on the phones, and quite honestly I have been treated like a ******** when it is their staff that committed the ******** acts! It is shocking and disgusting