I note that since the military coup last week in Thailand, a number of links to betting sites have been blocked including Betfair. These things tend to wax and wane. It is not North Korea. What is blocked this week inexplicably is unblocked next month and then blocked again a few months later. What is blocked on True may not be blocked on TOT. The "mai pen rai" "can't be bothered" work ethic seems to extend to blocking websites too.
Moral of the story:- invest in a proxy server service. An inconvenience but it allows one to continue undisturbed.