All types of such operations that users can use the services of a bookmaker's office are described in detail in the rules of the bookmaker. The player and the office conclude a contract, according to which the bets will be made. There is a detailed description of the conditions under which the return and cancellation of the player's bet are carried out, but the main issues should be considered in more detail.
Reasons for bet cancellation
A match is declared abandoned. If a match is recognized as not held for any reason (weather conditions, force majeure), the bet shall be refunded, and the systems do not take this result into account. If a sporting event is postponed for three more days, the bet shall be returned.
If the match will be played before the specified 3 days, the bookmaker still reserves the right to make a decision to return the bet without waiting for the completion of the event, it informs the player in the official results. If the event is interrupted and not finished within the time specified in the rules of the bookmaker's office, all bets shall be refunded.
Error in the line. The bet is voided in case of software failures or staff errors when accepting bets (obvious typos in the odds, inconsistency in the value of odds in different positions, error in ensuring control over the change of odds in play, etc.). This point is clear insurance for the bookmaker, who solves his mistakes very easily, mostly at the expense of the player.
This happens, for example, when the office keeps a mirror image of the match, that is, the winning team is not the one indicated by the bookmaker, but another. Or keeping an online tennis match that takes place somewhere in a remote area, the bookmaker may make a mistake in the score, and subsequently, cancel the bet and return (at best) the money.
Also invalid bets bookmaker may declare a bet invalid if there are signs of an unsportsmanlike struggle or in case of violation of the rules of the game. The reasons are very subjective and again the player is in a losing situation, the office can simply cut bets, let's say placed on the basis of some unofficial information.
After all, everyone knows that offices do not like to lose and a stable winning player may cause suspicion of foul play. In case of frequent winnings, it is very easy to fall out of favor with the bookmaker, who will start to "press" the lucky player, and the cancellation of winning bets is the least of what the player will have to face.