I suppose my main questions I am hoping to get some advice/input about are;

1) What can I realistically expect from AP regarding this? Can I 'demand' that a proper investigation is done in to this? Are they obligated in any way to investigate this fully? Is there a process that they are obligated to follow or can they just as I stated to the AP rep yesterday "just hide behind the line that 'some parcels just do get lost'"?

2) Does anyone have any experience in getting AP to look in to these matters? I know they have what they call the 'Revenue Protection' team, but I believe this is for investigating parcel recipients and such who make false claims, or at least repeated claims. Or I suppose senders who do the same. 

Apologies if I am coming across stressed, it is actually causing me quite a bit of stress because I am reluctant to keep sending parcels using AP whilst I am unsure what is happening and without some assurances from AP that they are looking into this.