Thank you for replies. I have spoken to Consulate here in Melb and they think he has probably been detained due to too many trips over the border. They are checking up for me. I have to wait another 24 hours before I can report him missing but he will probably be deported back here. Just have to wait it out now.

I've had strange delays in email service going to and coming from Laos and suspect the Lao govt. may be causing these delays as a way to monitor emails. Laos is just as safe as Thailand and not a dangerous place so I wouldn't worry too much.

If he's on a Thai phone server, he may not be able to use his phone in Vientiane. It's only just across the river but the signal is unreliable.
Where is he? Vientiane or Savanakhet?

I used the Nagi of Mekong. They are a reasonable price and includes picking you up from your hotel,padded seats with table, always fruit and coffee,a lunch provided, and a hotel booked overnight. The public boats are much cheaper (with none of the extras) but I really don't think it is suitable for you. At the other end there are boats which are much more expensive and I can't see the difference. In case you want the email add. nagiofmekong.com

I just noticed your desire for the boat trip to be affordable and reliable and now think you won't find such a trip. The Mekong between LP & Vte. doesn't have any regular reliable public boat service. The only trips other than cargo boats are with super expensive luxury boats or a charter of the whole boat. In the article I gave you a link for the luxury boat didn't actually go from Vte but from a long distance upriver towards Pak Lay as the river was too low at that time. I suspect the Mekong will be even lower the next few months until maybe September when the rains come, especially since we think they have started filling up the reservoir behind the new Sayaboury dam and this would restrict water levels below the dam even more than normal.

I wonder if he didn't get surprised by the new rules about getting a visa from the Thai Consulate in Vientiane. We no longer can just show up and wait in line to be processed but must make an appointment via the internet in advance and the next times available are two weeks from now. Maybe he took a bus down to Savannakhet to visit the Thai Consulate there which would explain why he's been out of touch.

You may try to contact his friends in Thailand or If he uses Facebook app - you can post on his timeline to see if anyone knows where is he?

Thanks to both you. What I have since found is that Mekong River cruises are no only extremely expensive but don't even operate end July because the rivers are too low. I will check out your suggestion of the company. Binet when you say there are a number of boats, what are they and what companies.

Thanks
LibbyNZ

This company seems to be doing this trip and info here - https://www.pandaw.com/expeditions/laos-mekong/cruise-dates . A story from one of their trips in 2017 here along with pic of boat - http://jclao.com/lao-and-now-mekong-river-vientiane-thailand/ . I don't know about their reputation other than what this story provides.

As far as I know , there are only two companies who do this route and that only if the river is full enough. They obviously are looking at the well heeled traveler and charge accordingly. For Luang Prabang to Houei Xai there are any number of boats .