Computer says Nooo

I paid out some £3300 on my Halifax Credit Card, this showed up on my monthly statement. Two days later my card had a rebate of £2400. It seemed sensible to contact Halifax to see if my statement could be re-issued to reflect the real balance of £900. I'm told 'Our system doesn't allow us to do this'. Welcome to the nightmare world where humans are totally superfluous – the COMPUTER rules alone. Of course it's not quite that simple. Instead of being able to just pay off £900 & incur no interest I'm now obliged to either pay the £3300 and then next month I'll be shown a big credit which I can only eliminate by using the card all the time thereby making more money for Halifax from their levy on transactions or I pay off less than the full amount & incur Halifax card interest charge. Either way Halifax makes more money from their computer 'system'. I hesitated about this post because there is bound to be someone who comments about how lucky I am to have these options. That I don't deny but it is not the point. The point is that everywhere you turn computer driven business practices have the hidden agenda of 'rip off the customer'.Already this year I've had this experience with two insurance companies and an energy supplier where a rigid computer system, which cannot respond to their error, not mine, has caused me unnecessary expense to the benefit of the company concerned.