It is already stated on the previous replies that you probably tracing/detecting using multi-accounts which is strictly prohibited in most gambling sites. This is not only Bet365 gambling sites, but all gambling platforms and you should also spend more time to read and understand what is TOS content. Probably you can contact their support and tell the truth that you have a multi-account but you are not abusing the system. I hope that the gambling site will forgive or if not, find another gambling site and learn your mistakes.
If it's a double account then they won't pay the winnings. If the account is restricted to small stakes then the OP is not a double account but a player who has en edge on obscure markets (usually small leagues). Bet365 don't like that but at least they always pay the winnings unless fraud attempts (double accounts, etc.).
Selling and buying "second hand" Bet365 accounts is very common on Facebook, but even if you buy one they will quickly find out it's a double account according to your betting patterns (and as said previously it's almost impossible to find a VPN that works on their site).