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 T4500, 6 GB Ram, Avast Free v2015.10.2.2211, Comodo Firewall 5.12 w/D+, MalwareBytes Premium 2.0, MCShield, Super Anti-Spyware Free, SpywareBlaster, OpenDNS Premium, Keyscrambler Personal, Ghostery. CCleaner, Greenshot, Firefox (latest build), Google Chrome (latest build) and, various browser security tools.
When you do something, do it with a purpose and do it on purpose.