If you call World Remit on their advertised phone number (020 7158 5800) they are able to see that number even if it is withheld! I tried this (twice) from my land-line and once from an internet phone account and World Remit could see my number on all three occasions. Something to bear in mind if you call World Remit from someone else's phone!!
For me a landline is for broadband only these days, the spam calls put me off using one long long ago. I tend to use all my devices that way hardly ever make calls, partly because I have a slight stammer that gets worse when I have to use the phone.
I've never had a marketing call from Worldremit. I once had a phone call to check something. To be honest, I'm delighted with them, and their security does seem to be much better than Western Union.
Their website is very basic, it does what it is supposed to do and it does it very effectively, Western Union has a complex AJAX enabled site that achieves, at the end of the day, nothing more than WorldRemit. WorldRemit does the job at a fair price and in a very reasonable time-frame while looking after your interests and making sure you are fairly secure, they don't offer storage of card details which is a good thing, WU offer that option which basically makes your WU account more dangerous if you choose to store card data on their databases.