Forced to buy new decoder by openview agent even though existing decoder is fine

Have existing decoder. Came up with error 04. Contact call centre. Agent informs me there is nothing wrong with decoder, but I need to buy a new one because of age. I asked her where it states that decoder must be upgraded.....she cant respond. I ask to be xfrerred to supervisor, she puts down the phone. This is not fair business practice. At no point when we purchased decoder we were told that it must be upgraded after a few years.