The my(dot)avast(dot)com is completely separate from the billing department.
If nothing else you have the option of contacting you credit/debit card provider
and put a "stop" on the payment.
Dell Inspiron, Win7x64 SP1, Pentium Dual-Core, 6 GB Ram, Avast Free 2014.9.0.2018, Comodo Firewall 5.12 w/D+, MalwareBytes Premium 2.0, MCShield, Super Anti-Spyware Free, SpywareBlaster, Bitdefender TrafficLight, OpenDNS Premium, Keyscrambler Personal, PrivDog. CCleaner, Greenshot, Firefox (latest build) and, Google Chrome (latest build).
When you do something, do it with a purpose and do it on purpose.