Why are companies allowed to "steal" people's shares or am I missing something?

Many years ago I bought some shares in a company, only a tiny amount of course but today they are worth 156 times more but when new owners came in, they apparently own 100% of the shares in the company but they don't because I own some. Obviously less than 0.1% but why were they allowed to steal or absorb or ignore my shares rather than buy them off me or keep me as a minor shareholder?

They were delisted and then relisted some time later, they were on the LSE.