[SOLVED] Two problems if customer pays later and changes payment method

-- HikaShop version -- : 4.1.0
-- Joomla version -- : 3.9.6
-- PHP version -- : 7.2

Hi,

Conditions:
- In system config, both "Payment of orders not paid immediately" and "Allow customers to change their payment method after checkout" are set to "yes".
- Multiple payment methods, e.g. Bank Transfer without extra cost, PayPal with 2% "price", Cash on Delivery restricted to Pick-up/Self-collection.

Problems:

1a. If customer selects Bank Transfer in checkout but later clicks "Pay now" and then chooses PayPal, the 2% are not applied.
1b. Vice versa, if payment methods are set for e.g. PayPal at no extra cost but Bank Transfer having a price of -2% (factually 2% discount), and customer selects Bank Transfer in checkout but later chooses PayPal, he is still enjoying the 2% discount for Bank Transfer.
I can see that the "price" amount is stored in #__hikashop_order in "order_payment_price" column, but it seems the customer changing the payment method does not "reset" this to then apply the price of the new payment method.

2. If a payment method is restricted to e.g. a certain shipping method (like Cash on Delivery restricted to Pick-up/Self-collection only), it is still offered if customer chooses to pay later even if a different shipping method had been selected (e.g. Airfreight or whatever). Haven't tried other restrictions, but at least shipping method restriction does not apply for "Pay now" (= later).

Both not good, obviously. Again, thanks in advance for fixing it.

Thank you very much for your fast and excellent intervention, Nicolas. It's working well now.