If the bet was accepted, it should be paid out in full - according to the odds that were available at that moment.

All bookies heavily protect themselves behind a huge TOC wall which basically allows them to freeze your account, cancel your bets, limit your betting positions - they can do whatever they want.

It is our fault we accept it but it's a good thing we have many to choose from, so when things like these occur you make a mental note and pay attention where you play next time.