First, contact your card or payment provider and notify them that you did not and do not wish to purchase these products and thus this is an unauthorised transaction. This is the fastest way to ensure you receive your money back.
Take screenshots where possible (of technical glitches, invalid phone numbers etc). AVG are well aware of these issues and have been for an extended period of time.
If for some reason you need to talk to an AVG representative, leave a review on TrustPilot. If you receive a reply from AVG by email then request your support ticket stay open until completion (otherwise you will have to repeat the process on TrustPilot to get to speak to somebody).