I've only had two issues.
There was the time some receptionists could not find my repeat prescription so eventually one said it had been passed to the chemists; and could not answer my query as to why and who had gave them permission, except to lie and say they all went to the chemists now. This resulted in me having a disagreement at the chemists about how they had my prescription because the receptionists had told me they had, and them denying it. I was furious, given the run around, and still no medicine. A return to the surgery the next day and apparently magic, suddenly the prescription was at the surgery after all and I'd been blatantly lied to.
The other time the prescription was again not waiting for me but at least that time they admitted they couldn't find it, and I had to go back and get it later that day.
But no problems at the chemist. You gave them the prescription, wait, and eventually they give you the medicine. (Unless you count the time I was charged as usual, only to find out the next time I had been old and venerable enough to have got it without charge :-( )