I read that shareholders in delisted companies could not claim...

I read that shareholders in delisted companies could not claim their loss ie tax deductions whilst still holding the shares.They were unable to because they had not realised the losses. According to this forum that I was reading there exists a company that buys delisted shares for a charge to enable shareholders to make loss claims for taxation purposes.
With that horrible thought in mind..would a change of name then allow shareholders in MFS to claim losses and start affresh with OCT shares at say 99c.??
Anyone know something about this?