I'm time traveling to the future to help you with the same dilemma. All I ask is that you visit www.coffeemedley.com
PayWhirl will do this. Here is a helpful link https://docs.paywhirl.com/en/articles/22113-how-to-automatically-transition-customers-from-one-plan-...
I'm using a version of the following from PayWhirl Support.
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Set up payments and shipments
You can chain plans together on PayWhirl to create custom billing/shipping frequencies. In your example, you want to bill your customers monthly while shipping them coffee on a weekly basis.
Let's say you want to bill them $50/mo.
Plan 1 - Charges $50, places an Order and has only 1 installment then subscribes the customer to plan #2.
Plan 2 - Has a 7 day trial, costs $0.00 then places an order with 3 installments - then subscribes the customer to plan #1a.
Plan 1a (Completely different from Plan 1, but charges the $50 because four weeks have been fulfilled from Plan 1&2) - Has a 7 day trial, Charges $50, Places an order and has only 1 installment then subscribes the customer to plan #2.
Set up "Randomization"
PayWhirl is not able to automate the truly random selection of a product within a shopify category to be added to your weekly shipment. You could technically create "artificial variety", where you use Option 1 (Listed above) and create a different plan for each week, with each having a different SKU. In this case, the customer would receive a different coffee each week, but you would be selecting which they receive based on the SKU referenced in each plan; it would appear random/offer variety but you'd have control over it and it would be automated once you set up the plans on PayWhirl.
