"Doctors certificate for a carer's parking permit"

I look after an elderly patient of this surgery who needs help from carers. I do not live in London but last October I went to the surgery and dropped off the Hounslow Council form and a stamped addressed envelope with a note explaining what was required and providing my details so that I could pay if there was a charge. Nothing happened, so I emailed the surgery the form, but still nothing happened. In January, I rang the surgery and was told the process I needed to follow to get a doctor's certificate, which included me posting the surgery the form and another stamped addressed envelope. Three weeks ago, I received an email asking me to pay £42, which I did on my friend's behalf. I had a couple of phone calls before I received the invoice but I've heard nothing since. My 97-year old friend's need for care has increased since last October but I appear to be no closer to getting the doctor's certificate despite spending £42 three weeks ago. It's utterly appalling.