Thank you for being a loyal subscriber, we appreciate having you part of the community. The switch option is not available on older subscription (before 2015), but you can still change to a different special price. All you have to do is follow these easy steps: 
1. Remove the recurring payment in your Paypal 
2. Resubscribe to the promition you want through this link.

https://secure.healthymummy.com/28-day-challenge-signup-2017/