Ring Merthyr tydfil cemetries on 01685 725720, they are on Castle Street. I am not sure if Pant is a cemetery that is still open or not. The ones I enquired about where Cenfcoed and and ffrwd and are closed. They will advise you about how to gain the information you require. My graves where unmarked graves. So this could be in your case why you could not find them. Obviously you need the round the dates to be able to trace.
Good luck.