avast is normally handling tickets within 1-5 business days.
As it is very busy at the support department, it can take a bit longer.
Just have some patience and the ticket will be handled as has been explained in many threads on this webboard.
Yes avast has the right to bill you if you have auto-renewal enabled, which you likely have.
avast can't help it if the credit card is expired, as it is you who is responsible to provide the correct information and change things if needed in time.