Why mobiles.co.uk offer cheap deals?

[Nokinoki]

I'm thinking about buying Samsung galaxy s9 by mobiles.co.uk. The question is can they be trusted?

The thing is that they offer Samsung Galaxy S9 64GB Black with Vodaphone for only £30 which includes unlimited text, min and 16 GB DATA. (+£125 upfront cost)

It sounds awkward to me since buying only s9 with instalments is about £25/30. Also, I wasn't able to find this, as well as some other deals on Vodaphone website.

Phone: https://www.mobiles.co.uk/samsung-galaxy-s9

Any idea why they are so cheap?

 

[Nokinoki]

Wow, thanks for replay guys!

Ok so, I still don't understand how does it work I mean networks such as o2 or Vodafone are losing money because their monthly payments are bearly covering phone price, not even including a huge data pack which often are extremely expensive. Below there is a link to Vodafone which offer the same deal but for £55 a month and £49 upfront. So why would they offer a similar deal but for less? Gowing back to my s9 example. Does mobiles.co.uk act as a "Middleman" and at the end I will assign a contract with, e.g. Vodafone and in case of any problems Vodafone will be able to help me?

Vodafone: https://www.vodafone.co.uk/brands/samsung/galaxy-s9/#Midnight_Black/64

 

[Nokinoki]

So based on the link below, would you take that phone? S9 unlimited SMS + min + 16GB data. Also, I have a noob question but does unlimited text messages and minutes are applied to all networks. I'm asking because when you click on more info on phones with Vodafone network, under charges outside of your allowance tab, they say SMS Anytime any network: 35p per message.

https://www.mobiles.co.uk/samsung-galaxy-s9