You will have to treat the reverse transaction/credit to your account as a supplier refund.
You will have to create a Supplier Credit, select the supplier you used in the initial expense, select the date that the amount was credited back in to your account, select the expense account you used in the initial expense, enter the amount and enter the VAT code you used for the initial expense (Out of Scope), save and close.
You will then have to create a bank deposit, ensure that the correct bank account that the amount was credited to is selected, select the date the amount was credited to your account, in the received from column select the supplier you used in the initial expense, in the account column select the creditors account/accounts payable, enter the amount and in the VAT column select No VAT (0% Sales), save and close.
You will then have to link the supplier credit and the deposit together; create a cheque payment (this will not create an additional payment in your chart of account/bank account, in the Payee box enter the supplier you used in the initial expense, enter the same bank account you used in the initial expense, the date can be the same day you create the cheque, on the right hand side you should see the deposit and supplier credit you created, select add on the deposit, select add on the supplier credit and select save and close.
In relation to the VAT Code for your interest earned can you provide uss with a screen shot of what happens when you attempt to select a VAT code.