I first used TOT way back in December, 2005. Subsequently after a few years I switched to 3BB.
In July 2013 I signed on with True. Essentially since then my problem with the Internet improved dramatically. Whilst I still have problems at times, it is not often. Additionally, however, True's response is "second to none". In my opinion their "after sales service" is wonderful.
Frankly, even if I could get a cheaper cost elsewhere, I would not switch.