Exchange if you want, but I'm not sure here those reviews are coming up with that (nor where you're seeing these reviews).
There are multiple DVI revisions.
DVI-A (single link, analog)
DVI-I (single, digital + analog)
DVI-I (dual link, digital + analog)
DVI-D (single, digital)
DVI-D (dual, digital)
For >60Hz, you need a source capable (so DisplayPort is fine) and run to DVI-D (dual) cable & capable monitor.
If you're seeing people reviewing limited to 60Hz, you're looking at (and they've bought) DP to DVI-D (single), not DVI-D (Dual) - this can happen in error, or via blatant misrepresentation from sellers.
Looking back at my original suggestions, I've actually made the same mistake & linked DP to DVI-D (single)....
To show you what the pins should look like, look here:
http://www.cabledepot.com/05MByCoDVI.html
This one has the pins for DVI-D (dual), but the extra pins in the middle (see pics, DVI-D single vs DVI-D dual) are fairly commonly faked (and as the answered questions indicate, it can't run above 60Hz @ 1080p.... so it's DVI-D single, deceptively posing as dual).
https://www.amazon.co.uk/UGREEN-Support-Connecting-Projectors-Displays/dp/B00B2HOVAA/ref=sr_1_1?ie=UTF8&qid=1490108195&sr=8-1&keywords=displayport+to+DVI-D+dual
This one is mini-DP to DVI-D (dual) and, even though you'd need yet another cable (mini-DP to full DP), it would work out cheaper if it's legit. It's clearly labelled dual on the device itself, but I've never heard of the brand, and there's no reviews.
https://www.amazon.co.uk/d/Electronics-Photo/LINDY-DisplayPort-DVI-D-Adapter-Splitter/B01F0VYI5G/ref=sr_1_4?ie=UTF8&qid=1490108195&sr=8-4&keywords=displayport+to+DVI-D+dual
Paired with:
https://www.amazon.co.uk/Rankie-Plated-DisplayPort-MiniDP-Resolution/dp/B01J8GUH5O/ref=sr_1_1?ie=UTF8&qid=1490108624&sr=8-1-spons&keywords=mini%2BDP%2Bto%2BDP&th=1
5.29 for mDP to DP and then 40.80 for DP to DVI-D (dual) = 46 quid or so.
You're looking at ~80 quid for a straight cable that can do the job:
https://www.amazon.co.uk/Dell-BizLink-DisplayPort-Adapter-Powered/dp/B003XYBA72/ref=sr_1_7?ie=UTF8&qid=1490108195&sr=8-7&keywords=displayport+to+DVI-D+dual
There are other 'off' brands for cheaper, but I can't confirm whether they are legit or fakes. The Dell one will work though.