False advertising?

My first three years came with the full On Star coverage of all their services. It’s almost the end of my free period and they lured me in with a 20% off discount code to renew my subscription. But when you enter the code, it says I’m not eligible for it and it puts the full price in the order. The representative says they can give me 10% off but not 20. FaceTime it. No on absolutely needs this luxury. Goodbye On Star. It was great while it lasted.