[corporate action]

I think I can answer my own question:-

Saga PLC went through a stock consolidation 1 for every 15. The price would have been adjusted accordingly. 

This is not a change by IG it's the company that's consolidated the stock. 

https://www.ig.com/uk/help-and-support/spread-betting-and-cfds/market-details/what-happens-to-my-shares-position-if-the-company-performs-a-sto

[corporate action]

I have  two buying and two selling movements on my Saga shares which are described as Corporate Action . This commenced  over a period running from 17th sept and ending on 23rd Oct. I'm trying to understand the logic of the quantities involved and how I appear to have lost the vast majority of my share holding.  Is this some value realignment?