What weve started doing is every year doing a small letter in january to our customers, detailing when last price went up by way of price review. Even if price doesnt go up it marks the date as being a review. Its easier to see on our records then when the price went up, and then when it does go up we remind the customers of how long its been as they often say "oh you only put it up a few months ago" when it was actually 3 years back!!
Think we are going to wait until next xmas and put them up by 10-15 percent, its been 2 years since the last increase, but that was about 15 percent then. The cost of living has gone up alot, a heck of a lot, but the price increases are far more than the usual wage increase your employed person gets.