i was told only 1 warranty exchange so waitr till 2 years is almost up
You were told wrong. Some folks have had their dealers feed them the same BS on chrome parts, only one part and only one time. I'm sorry, but that is not how warranty works, and that BS is not supported by warranty law. See, that's the fly in the ointment for Harley and the crooked dealerships, at least in the USA they have to comply with Federal warranty laws.
If they were talking about a problem that didn't fall under warranty but they were taking care of it as a goodwill adjustment, then yes it would make sense if they said they would take care of it only one time as a goodwill measure. But when it is a definite defect, which this seat deal definitely is, then it doesn't matter if they replace it 6 times and it fails again within the warranty period, they still are obligated to replace it. One might hope they'd get the seat supplier to fix the root cause of the problem before having to replace a seat 6 times, but considering the company we're talking about who knows?
Don't let them put you off. If you continue to ride two years it will continue to get worse, and then they might point out any obvious wear and tear on the rest of the seat and tell you it's just regular wear and tear, you'll have to pay. More than one crooked place has pulled that sort of stuff over the years. Regardless, get it documented in writing and photo's, and if the dealer jerks you around find another one or go straight to H-D and bypass the dealer.
Jerry