Post office refusing my pre-paid labels because

Hi, i wont dabble into long descriptive details, but I have an ongoing issue with my post office.

I currently send out around 15 parcels a day with them (or used to), and use the drop n go service with them, so i pay them beforehand on a prepaid royal mail card and they process it when they are not busy. However, as my order list grows, i often get missing parcels or late deliveries from royal mail, and to chase orders up, i had to sift through almost a hundred of receipts and keep them organised. As my business expanded to almost 25 parcels a day at its peak, the amount of late deliveries and lost item grew, and as a result, it came to the point i was completely not bothered to chase tracking details etc and simply issued refunds (bear in mind these are £10 items, so could take a hit to save time/headache) And I knew that if the item had not arrived to the customer by then, it as definitely lost.

As a result, i decide to use pre-paid labels through Amazon, not only do i save around 5p a parcel (after including ink and paper costs) , I can quickly chase tracking numbers with a click of a button, and also track compensation from royal mail if theyre undelivered after 30 days (or 60 days?).

So i take a prepaid batch of packages to the royal mail and i quickly noticed the post office clerk gave a sharp bulldog look that had chewed on a wasp? He exclaims that ‘we dont get paid for handling these.’ And i respond by telling him, arent you paid hourly by royal mail. And he then said 'yes but we get commission of your other parcels without pre-paid, around 7p a parcel.

I said sorry but this is because of consisntely missing parcels and lots of receipts, and this is not only cheaper but more convenient. He took the parcels albeit and literally DUMPED them on the floor so loud, i could hear the bottom parcels become flattened. So then i shot him a look as to say ‘is there a problem,’ but i quickly decided not to pursue this. I am good at sensing other peoples emotions and i could tell for some reason he was disproportionately unhappy with myself. I decided not to pursue this, and ask what the problem was and left.

So the next day, i arrive again with parcels anda different woman working at the clerk flat out refuses to take my parcels saying royal mail dont process these 2D printed labels. She said I would have to take this 20 miles away to their depot for processing. I asked what happened to yestedays parcels and she said ‘we put it through but fingers crossed they process it’

Now i confirmed with a buyer if he received them, and i know for a fact the prepaid labels are going through fine, Do i take this as the clerks definitely dont want to process my prepaid labels at all? All i ask is for them to put it in the sacks and not scan or anything. Do i trust with them my parcels?

Shall i go for an ultinatum tomorow and ask what their problem is with prepaid labels?

thank you