Wrong shipping and payment method

[TaDrik]

Hello to all.

I am facing the below problem.
The customer chooses in cart a payment and a shipping method.
When submiting the order in the thank you page the methods are correctly showing.
In the order overview page and in the order confirmation email both are wrong. Both are showing different.
For example: The buyer chooses "Cargo" as shipping method and "Bank transfer" as payment method. In the order overview and order confirmation email appear "Courier" as shipping method and "Pay on delivery" as payment. Not the same every time. I mean that it does not replace a single payment or shipping method with the same. It is random. In all the replaced methods the descriptions are not these that I have. The descriptions are from an older version of the shop. (Migraded to the current version) Checked the DB and they do not appear in any table.
It worked fine for about a year. The problem started about 1 week. The owner says that he didn't change anything. (As always)

The VM version is 3.8.9