"Prescription problems"

I put my regular repeat prescription in as usual earlier this month. Went back to chemist 3 days later only to be informed that I had put prescription in too early, so it had not even been actioned, and that I had to put it in again. Very frustrating as I had to wait another 4 days before picking up my medicines. I have already had meetings with the practice manager and changed chemists due to previous problems. Practice manager assured me last year that there would be no further problems, yet they persist. Also assured by one of the GPs that my arthritis medication would be added to repeat but it has still not been added, despite repeat assurances.