I'm afraid the tour operator appears to be fully within its rights to keep 100 per cent of your money, which is the usual penalty for such late cancellations.
Harsh, but your decision to cancel is classed as "disinclination to travel". Your fears about the floods - and the opinion of your Australian friend - carry no legal weight. Neither does the Foreign Office advice against travel to Bangkok (though not to the international airport) as of Wednesday, after the date you were due to fly.
Tour operators can make changes to a holiday to cope with unexpected events, and I imagine the firm deems the two days of alterations to the schedule a "minor change" - in the same way cruise firms will sometimes change scheduled ports of call without compensation. It is regrettable that the operator did not let you postpone your trip. Most airlines are allowing people booked to Bangkok to change plans without penalty. You could apply moral pressure, asking for the return of the taxes, fees and charges you paid and a proportion of accommodation costs. But the firm is within its rights to keep these.
Email your travel queries to simon.calder@standard.co.uk
