£ 150 is too expensive considering that you will only get 7.867 miles for the return flight. Then it would be cheaper to buy the miles. In March, 7.800 miles are sold for € 155.
Unfortunately, I have 41.000 miles at stake (FRA-BKK-FRA)
The only alternative to Thai seems to be SIA via Singapore. This would triple the travel time and probably also the price.