Answer: Thank you for writing. Monrovia is a wholesale-only nursery and sells its plants to independent stores. Each retailer has its own individual policy about guarantees. So any guarantee would be up to the store where you purchased the plant.
I might mention that butterfly bushes are considered hardy into zone 5 and the colder it is the less reliable they will be. You live in a nominal zone 5A (based on your zip code) which is the colder part of zone 5; depending on the microclimate where you planted the shrub, it might be as cold as zone 4 -- a windy, exposed, rural location for example could very easily be zone 4. If you try again with a Buddelia, keep in mind that these shrubs tend to handle cold better when they are planted in a sheltered location with very well drained soil and heavily mulched in late fall. In zones 5 and 6 it is not unusual for them to die back to the ground or close to it each winter, then regrow from there each summer.
I'm sorry about your shrub.
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