Ive been dealing with VOSA now as a tester. then QC, then AE for over 18 years, if you are testing to the required standard, keep the paperwork as it should be, and generaly work by the book you will never have a problem with VOSA.
I have had spot checks, re-tests, appeals and have a station that is rated one of the highest in the area.
though recently I had a telephone review, which was obviously carried out by a non vosa call centre, as when I queried the stats they had no response for me.