Where are you getting this? The last and third volume to Motto Hinekure Chaser has been scanlated, it's right up there with the rest of the chapters. Technically there's four volumes to the whole series, Hinekure Chaser being the first one and the last three titled as parts 1, 2, and 3 of Motto Hinekure Chaser. Motto Hinekure Chaser volume 3 technically starts at chapter 12 and ends at chapter 17 with a couple of extras.
Yup the site is correct, volume 4/volume 3 of Motto Hinekure Chaser! is the last volume and was scanlated. Check under the releases, it says Chapter 17 (end) was released 4 months ago by Pink Cherry Blossom Scans. End in parenthesis generally denotes the last chapter of the series (not including extras). Volume 4/volume 3 contains chapters 12-17. There's one more extra in this volume that is to be released, but that should be it. I hope that clears it up, but let me know if you're still confused.
I'm confused, is this manga really completed? I don't think the lasst chapter felt like the last one, but maybe it was?