@Westie
As b*cat and other forum members have said, there is a connection with LLU provision and the availability of BTw test facilities, not sure who your telephone line rental is currently with but your line data as FTTC will be provisioned through BTw regardless of ISP, obvious esception to this being cable, not usually referred to as FTTC (Virgin Media).
There are a few Vodafone ISP active forum members, I'am sure they will be able to offer more definitive advice.
There was a period at the end of last year, at least 2 to 3 weeks, when the BTw Performance Tester (further diagnostics) was not working or at best produced a very high failure rate, there's quite a long thread on the Plusnet members forum regarding this, one of the PN staff members was very diligent in his contacts with BTw and eventually the issue was sorted.
I have experienced virtually 100% success rate since it was fixed, in fact much better that it ever was previously when 50% failure rate was not uncommon.
The "mouselike.org" facility depends on the ability to extract the information from BTw (as it says in the test narrative), during the time period when the BTw Performance Tester (further diagnostics) was not working "mouselike.org" (BRAS profile) would not work either.