Subscription renewal

My subscription has ended. When I went to renewal I was charged £160. I how much AVG for a new subscription and found it to be a lot cheaper. I had paid for this and obtained a renewal code. Although when I went to use it it did not work. Has anyone had a similar experience and why do have to pay many times more than new customers looking for the same product. It seems to be a case of loyalty cost more than shopping around.