Avast review: Antivirus subscription

For over a decade now, I have unknowingly been double-charged by Avast for their Premium Security (antivirus) subscription i.e. I have two paid subscriptions for the one service. The company never alerted me to this until I had to trawl through my account documents to find out for myself. Moreover, when I contacted them asking for an explanation and any chance of recompense, they stubbornly referred my to the "30-days, then no money back" policy, whatever that means.
To make the situation even worse, I now find my paid subscription has been completely cancelled and I am back on a free unpaid antivirus product, yet I have still paid for the previous $100/year product. This is even worse than simply being owed large sums of money and compromises my business. I will not be loyal to this company again for their dishonesty. and I will do my utmost to expose their bad behaviour via this, and other online means.
To other customers - be very careful and check your account details and structure, in case you too are an unsuspecting victim of this typically modern crooked behaviour that so many tech firms undertake.