The number you have called is not avast but a third party company and they really suck.
There are a huge amount of complains about them.
I suggest you never call them again.

avast is using two companies to handle financial transactions.
Nexway and Digital River.
Sending you to Digital River is another indication on how bad that third party company is.
What they should have done is sending you to Nexway, the avast ticket system or here.
https://support.avast.com (the ticket system)

Disabling auto-renewal should be done through the order information.
https://www.avast.com/find-order
Paypal can’t do that.
They only can make a transaction undone.