Integrate Infusionsoft with GoCardless.com

General information for the business: We sell marketing services to business owners in the UK
Description of requirements/functionality: We are heavy users of Infusionsoft, including running subscription services through it. We've found the integration with UK card merchants to be rubbish. Even with a specialist integration service, the payments fail too frequently..

I'd like to set up all future subscription payments to be through GoCardless.com. This is a fantastic UK Direct Debit service which works perfectly.

However I'd like payments to be controlled through Infusionsoft. Both services have great APIs.

We are prepared to use Infusionsoft's Campaign Builder to control the monthly payment request, so we can sidestep Infusionsoft's limited subscription functionality.

We'll need to ability to regularly set up for different services and different amounts of money.

You are likely to be an experienced Infusionsoft developer

Infusionsoft API: https://developer.infusionsoft.com/

GoCardless API: https://developer.gocardless.com/#introduction

I have no idea how much this will cost, so please ignore my guide price

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ANSWER TO CLARIFICATIONS
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PPH makes it very difficult for a buyer to answer clarifications :(

Question: What is the budget?
There is no budget for this. It needs to be done by someone competent with APIs, who can help support us down the line if Infusionsoft or GoCardless change their API and break the integration

Question: What is the workflow?
1) Client fills in an Infusionsoft webform on a page such as this: http://www.opticianseo.co.uk/get-started/?Contact0_OpticiansSEOprotectedarea=Oxford

2) When they go to a payment page, it's would be a GoCardless page rather than the Infusionsoft hosted card payment page: https://ph.infusionsoft.com/app/orderForms/74224b8b-25d6-4c22-9e65-f43924ab9291. We'll need to be able to carry data between these pages of course

3) GoCardless allows you to take a payment now, and simultaneously set up an authority to take future payments

4) This successful payment will then trigger the start of a Campaign in Infusionsoft, that will automatically send a payment request to GoCardless every month

I can handle stuff like building the Infusionsoft campaign. It's just integrating the 2 systems that's impossible for me