Telephone research: calling retailers to get delivery info

I need you to call 31 retailers based in the UK to find out which carriers they use for delivery of things purchased on their web site. The info is not on their web sites so it will require a call to their customer services or other number.
Most will be fairly quick, but a few will be hard to get hold of, and one or two may not be possible.

The main thing that I want to know is which parcel carriers they use for standard / 2-3 day delivery and for express / next day - and also what click and collect options they offer.
A few will offer other services, such as international delivery, same day delivery or two-man delivery (for big/heavy items, furniture, TVs, etc) and I'd like to know who they use for those as well where they do them.

I'll provide a list of the retailers with their websites, but don't have phone numbers - getting the number is part of the task.

It should take between half a day and 1 day to do it.

To show me that you have read the brief (many people don't), please start your response by naming the large online retailer with the same name as a very big river in South America.