Prevent refunds from being greater than the refund value

[zoecrosby]

We have an issue with Storm integration where by the user can take a payment using Storm that is less than the actual transaction in IMS. e.g. IMS asks for £20 but the user only entered £10 into Storm so a payment of £10 is taken. In this scenario IMS is up on the bank by £10 so we have to manually add a transaction into IMS for -£10 so that the IMS and the bank balance. If a refund were to be done on the initial payment it would allow £20 to be refunded
a) because SmartPayFuse allows refunds greater than the actual payment and
b) because IMS doesnt take account of the -£10 transaction thats allocated against the same PSP reference.

Can we update the refund process to ensure that the refund amount is not greated than the total for all transactions with the same psp reference

[bmbc-dev-detec]

After discussing this with Zoe we're happy that this issue is primarily a concern for the Storm integration, and that will be removed for BMBC in the near future. The IMS API does accept an 'AmountPaid' value in the Api.Controllers.PendingTransactions.ProcessPaymentModel. We could use this value to check that the amount paid matches the total of the transaction it relates to - to double check. And if it doesn't we could flag it somehow and allow the user to deal with it. How they'd deal with in needs to be flexible - some councils may want to move the payment into some kind of suspense table, otheres may decide to refund it. We need to discuss this with the wider IMS community to determine the most appropriate solution.