First question: what disciplines do you calibrate for? That will help in directing you toward a solution.
Next thing to understand regarding proficiency testing and inter-laboratory comparisons (PT/ILC). Accrediting bodies (ABs) can EITHER accredit PT providers OR offer PT themselves, but not both.
Now, if there is no PT available, and if there are no labs available that do the same thing so you can complete an ILC, then the other examples kick in.
First thing to do is read the verbiage in 5.9.1, and remember that there are other ways to comply.
PT/ILC is directed - where available - by ILAC/APLAC because it is a bookmarking of the lab against other labs with a comparable scope.
If you have selected an AB, then ask them whether they have any available.
Hope this helps.