Oh also!
If you are referring to CFDs, indeed T212 does have a control on the spread there.
But the heightened spread that will arise with volatility is not an effort to sham their customers, but instead a necessary step regarding their risk-management policy.
As a CFD provider, they are your counterparty, and while they keep a market neutral position (they are not betting against you), they may face high risks when underlying securities move rapidly, and if liquidity is low. Risk being them not being able to replicate your position with the real market, and hence being heavily liable towards you without any of their cover; or the opposite; you becoming far more so liable to them than anticipated.
Now imagine that for every one of your bet, your broker is the counterparty to thousands more bets, from thousands more customers, all at once.
Nobody would enjoy seeing their broker fail, and not being able to honor their counterparty agreement towards their customers.
This is why in certain situations, on CFDs, spreads are very high, as it is standard procedure to limit risk exposure when some underlying security face liquidity risk or execution risk.