[mothered]

but if I say that part of the ordered item is missing, they should still carry out internal investigations .... or not do it and refund me ... right?

There are no hard and fast rules with Investigations- some companies Issue an Instant refund, whilst others go through the Ins and outs of the claim with a lengthy process.

As stated In my above post, there are various factors that determine whether an Investigation Is opened but rest assured, It's simply part of company protocol to move forward with the claim. As such, the majority do In fact result In a successful outcome.