Errors and glitches in online banking app

When trying to buy electricity through my online banking app, I kept on getting general errors. However, when I checked my account balance, I realised that, even though the transactions where unsuccessful, Standard bank was still taking money for said transaction off my account. A similar glitch happened before when R300 was taken off my account as a result of an unsuccessful transaction (3 days ago) and when I phone them, they are still \investigating". Apon phoning the call centre to find find out what was going on and why they will still taking money off of my account even though these transactions where unsuccessful"