We get complaints every year, but the percentage is very small, and that's what Sage is counting on. If someone is on Silver, I've been known to recommend going to Gold, because it's not that much higher and you get much better benefits. That actually works.
The other answer I have is go to monthly payments. One of our larger customers that licensed on the old 3-year payment plan (software and service) was faced with a $30K+ bill, complained, but accepted the monthly payments.