Whats the issue with getting your home insurance company to complete the silly form? Is this being refused? Obviously the directors signature isnt gonna happen, but how would that be checked anyway..? Get a helpdesk agent to fill it in, and their direct boss - doesnt seem too hard 🤷♂️
I attempted this for the METV: 6month bank statements and other financial evidence - all has to be one upload, and still under 500kb.... Its impossible. As Robert says above, just send a load of illegible shite.
the point is airlines in the UK can (and do) refuse boarding if you dont have a return flight (or a return flight within the term of your entry stamp). They should call the airline for assurances that they will be allowed to travel(and get a letter to state as such, to present at check in.) There would be no issue at thai immigration.
You wont get a third 60 day stamp as the visa had expired. The re entry would have only maintained the end date of the extension - which as you were staying out 1 month from the 28th it would have also expired.