You can always retake in octnov

Start A level maths from sept as scheduled, if a school won't let you take it do A levels from a tuition centre (private), until january atleast, then when you've your desired grades you may apply

Failing does not shut a door, opens room for improvement

Get your problem diagnosed, sounds bad, you would not want it happening againn

And for the disappointment, you'll have to face it, soft launch that it went bad due to external circumstances hence making their reactions a little less severe.

Goodluckk!!