flbymike,
To keep it simple, if you have flown 12 hours SEP (6 as PIC etc) in the 12 months preceding the date of SEP rating expiry, all you need to do is to fly your MEP proficiency check with an Examiner before the expiry date of your SEP rating as it an acceptable substitute for the SEP 'dual training flight' requirement. That will both revalidate your SEP rating 'by experience' and revalidate your MEP Rating if flown before the expiry date of your MEP rating.
Your Examiner should darn well know that!
But if you cannot meet the SEP 'experience' requirements,or if you go past the expiry date of your SEP rating then you will need to fly a revalidation or renewal proficiency check on a SEP aeroplane in addition to the mandatory MEP proficiency check.
As for yout FTO's policy concerning the 'dual training fight' content, go somewhere else and discuss with an FI what you wish to refresh.
And pielander, you're not correct. The content of a SEP re-validation proficiency check is identical to a SEP renewal proficiency check. The full PPL Skill Test is NOT required to be flown if the SEP rating lapses, just the SEP renewal proficiency check - so the Examiner's fee should be the same, not '50-100% more'.