My office said the same but DLT requested the cert of residence and they rang me when they had it so I could go and get the license. The reason given was that it saved time. Seeing as you go through exactly the same process for tm30 as for cert of residence it seems daft that DLT will not accept tm30 receipt.
You have proof in the form of stamps in your old passport that you did not overstay. You saw a chat with a Thai immigration Official; why not try sending the proof to them or to a lawyer who should be able to sort it out for you?