HTML expert to help with Chargebee integration

Ideally looking for someone who has successfully worked with Chargebee subscription service and with expert HTML dev experience. It's a fairly small job but it's the last remaining hurdle in a job I've been working on for a client.

We have an ecomm site which uses Chargebee to manage subscriptions, and as part of their service they provide a checkout and portal function. We need some code to change the functionality of the checkout slightly. Chargebee have provided me with example code but I'm unable to make sense of it (I have designed the site and our usual developer is unavailable for the next 2 weeks) so we need someone to step in!

Obviously I'll provide more details for those who apply and tt is fairly urgent so will need to start the work this week,

many thanks