I bought a share on Exchange A with my platform on the usual terms: legal ownership is the platform's and beneficial ownership mine. I've now been told by them that Exchange A is delisting the security.
They tell me that to avoid a serious risk of being unable to sell the share I must now sell it on Exchange A and buy it again on Exchange B, which continues to list the share.
This seems to me to unnecessarily incur dealing costs. What is to prevent someone from buying a share on one exchange and simply selling it in due course on another?