Changed the deal without notice

I have been with Virgin wine for years and in addition to my monthly interest I, like other wine club members, received 20% interest on whatever wine I purchased along with free delivery - it was a really good arrangement and I enjoyed the wine. However, Virgin have changed the deal and no longer offer the additional 20% on the monthly purchase and they made with change without advising me, in fact I don't think they advised anyone. I talked with my wine adviser who got a little ratty with me and told me that the new arrangement had been in place for 18 months but I know that it only changed this month. I have decided to discontinue my arrangement with Virgin - I have lost trust in the company. Shame.