no post slip to collect

Hi

I have several parcels that has ARRIVED at wierda park post office, been a month now no slip sent to me to collect my parcels, I give them the tracking number, they say it cant be tracked with that number, how is possible I can track it with that number on when and what time it arrived at wierda park post office, are we lazy to look though the post to find it, maybe we shouldn't be working there, surely all my parcels can found using my name, surname, cell number, address or something, POST OFFICE is not a small business.......

Thanks