What happens to held up EMS mail?

I was expecting to receive my UK drivers license and counterpart by EMS sometime this month, a family member was forwarding it from the UK. They used international track + sign from Royal Mail.

I learnt today that Thai post attempted delivery on 17th but because or a minor admission in the address (excluded Moo 1) they just gave up, interestingly the postmaster knew exactly where I was staying and just laughed (the specific in the rest of the address were clear enough) at the omission.

July 14, 2014
10:17:10 LAK SI MAIL CENTER Accept July 14, 2014
14:27:34 LAK SI MAIL CENTER Items Into Container July 14, 2014
14:27:41 LAK SI MAIL CENTER Dispatch July 15, 2014
16:38:39 CHUMPHON MAIL CENTER Items Into Container July 15, 2014
16:38:45 CHUMPHON MAIL CENTER Dispatch July 16, 2014
13:47:10 MAE NAM Container Received July 16, 2014
13:54:54 MAE NAM Items Into Container July 16, 2014
13:55:04 MAE NAM Dispatch July 17, 2014
11:00:52 CHAWENG Out for Delivery July 17, 2014
09:00-11:59 CHAWENG Delivery Status Scheduled delivery attempt due to Incorrect Address Scheduled delivery attempt due to Incorrect Address Scheduled delivery attempt due to Incorrect Address July 26, 2014
11:23:00 CHAWENG Items Into Container July 26, 2014
12:33:18 CHAWENG Dispatch July 26, 2014
21:25:58 CHUMPHON MAIL CENTER Items Into Container July 26, 2014
21:26:02 CHUMPHON MAIL CENTER Dispatch

The postmaster initially said I have to "write" a letter to Chumphon to get them to reforward it but he mentions it may have already been returned to sender.. He didnt have the address of chumphon mail center, after a few face palms he did note the particulars however not convinced he can do anything.

Problem is compounded because the person who forwarded it say they did not give the UK post office a return address.

Giving the RNXXXXXGB tracking code to royal Mail say they cant do anything yet and Thailand Post aside from the write a letter to chumpon dont reply to email.

Any idea where this will end up? I suspect if it was to be returned to send it would have to go via Bangkok first? Is there anything I can do other than wait and see?

What happens if the envelope doesnt have a return address?